Systems and methods for angular direction indication in wireless communication

ABSTRACT

An integrated terrestrial/non-terrestrial network may allow for enhanced network coverage. However, there are control and management challenges associated with an integrated terrestrial/non-terrestrial network because the network and user equipments (UEs) are no longer confined to only using conventional cellular communication via terrestrial transmit-and-receive points (T-TRPs). One challenge is how to perform beam management. In some embodiments, methods and systems are disclosed in which an indication of angular direction (e.g. beam direction) is provided by the T-TRP. The indication of angular direction may be used by a UE for communicating with a non-terrestrial TRP (NT-TRP), e.g. using beamforming. However, the methods are not limited to integrated terrestrial/non-terrestrial networks or the involvement of NT-TRPs, but apply more generally to indicating angular direction for directional communication.

FIELD

The present application relates to directional communication (e.g.beamforming) in a wireless communication system that may include bothterrestrial and non-terrestrial transmit-and-receive points.

BACKGROUND

Current wireless communication systems are largely based on terrestrialsystems. The user equipments (UEs) may move, but the network'stransmit-and-receive points (TRPs) are terrestrial, e.g. typicallystationary, mounted on a tower or structure connected to the ground, andnot easily moved. This limits flexibility because terrestrial TRPs maybe difficult to install in some areas and may be difficult to relocateto areas with high-demand.

A wireless communication system could alternatively or additionallyemploy non-terrestrial TRPs. A non-terrestrial TRP is a TRP that movesthrough space to relocate, e.g. on a dynamic or semi-static basis.Examples of non-terrestrial TRPs include TRPs mounted on drones,balloons, planes, and/or satellites.

A wireless communication system that includes both terrestrial andnon-terrestrial TRPs will be referred to as an integratedterrestrial/non-terrestrial network. An integratedterrestrial/non-terrestrial network may allow for enhanced networkcoverage. For example, if there is a temporary high demand on aterrestrial TRP, e.g. because of a large gathering of UEs in onelocation, then a drone having a non-terrestrial TRP mounted thereon maybe able to fly over the gathering, thereby increasing communicationcapacity by allowing for communication between the UEs and the networkvia the terrestrial TRP and/or via the non-terrestrial TRP.

However, there are control and management challenges associated with anintegrated terrestrial/non-terrestrial network because the network andUEs are no longer confined to only using conventional cellularcommunication via terrestrial TRPs. Instead, non-terrestrial TRPs maymove through space across different cells and temporarily assist withcommunication between the UEs and the network. Additional control andmanagement considerations are required in order to effectively deploythe non-terrestrial TRPs. In particular, directional communicationpresents challenges unique to non-terrestrial TRPs, due to theirchanging positions.

SUMMARY

One technical problem recognized by inventors is how to perform beammanagement in integrated terrestrial/non-terrestrial networks. In anintegrated terrestrial/non-terrestrial network, directionalcommunication may be implemented by the UE and/or by a non-terrestrialTRP (NT-TRP) and/or by a terrestrial TRP (T-TRP). The directionalcommunication may be implemented using beamforming. Transmit beamformingrefers to directing a transmission in a particular direction byperforming signal processing to cause the transmitted signal toexperience constructive interference in the particular direction. Thesignal transmitted using transmit beamforming may be referred to a beingtransmitted on a transmit beam. Receive beamforming refers to performingsignal processing on a received signal in a way that causes the receivedsignal to experience constructive interference in a particulardirection. The signal received using receive beamforming may be referredto as being received on a receive beam. If two entities arecommunicating with each other using beamforming, then ideally there isbeam correspondence, i.e. the direction of the transmit beam correspondsto the direction of the receive beam. However, beam correspondence isnot a necessity, and moreover it might even be the case that one entityimplements beamforming and the other entity does not.

A non-terrestrial TRP (NT-TRP) may use beamforming to communicate with aUE and/or with another NT-TRP. A UE may use beamforming to communicatewith a NT-TRP. The following problems may occur. How does the UE knowthe direction in which to perform transmit and/or receive beamformingwhen communicating with a NT-TRP? How does the NT-TRP know the directionin which to perform transmit and/or receive beamforming whencommunicating with one or more UEs? If two NT-TRPs are communicatingwith each other, how do they know the direction to perform transmitand/or receive beamforming? To help address one or more of theseproblems, beam sweeping methods could possibly be used, similar to how aT-TRP performs beam sweeping in the downlink direction to transmit asynchronization signal block (SSB) in multiple beams. However, beamsweeping has relatively high overhead because it involves multiplebeams, each in a different beam direction, rather than just one beam.

More generally, regardless of whether NT-TRPs are present and/orregardless of whether the wireless communication system is an integratedterrestrial/non-terrestrial network, if directional communication is tobe used by a first device to communicate with a second device, how canthe angular direction for the directional communication be communicatedto the first device?

In some embodiments, methods and systems are disclosed in which anindication of angular direction is provided in an absolute way, e.g. interms of beam angle information (BAI). The BAI may be or include anangular direction, which may be a quantized angular direction selectedfrom a range of angular directions. Overhead associated with beammanagement may possibly be reduced, e.g. by possibly avoiding beamsweeping in some instances. For example, instead of a UE using beamsweeping across different receive beams to determine which receive beamdirection has a suitably strong signal for communicating with a NT-TRP,the UE may use BAI associated with a NT-TRP to implement a receive beamin the direction of the NT-TRP. The BAI may also or instead be used bythe UE in order to implement a transmit beam in the direction of theNT-TRP. As another example, instead of a first NT-TRP using beamsweeping to communicate with a second NT-TRP, BAI associated with thesecond NT-TRP may be used by the first NT-TRP to implement a receivebeam and/or a transmit beam in the direction of the second NT-TRP. Insome embodiments, a T-TRP may transmit an indication of beam direction,e.g. BAI, to a UE and/or to a NT-TRP. In some embodiments, a T-TRP maytransmit, to a UE and/or to another NT-TRP, an indication of thetime-frequency location at which to find a reference signal transmittedby a particular NT-TRP.

In some embodiments, the range of angular directions may be in the formof a set of quantized angular directions. The angular range maycorresponds to a certain region of space. In some embodiments, theangular range might only carry information in an absolute way about theupper bound and the lower bound of the angular directions to be used bythe UE. Individual quantized angular directions within the indicatedangular range may be determined by the UE, e.g. by uniformlydistributing quantized angular directions in the angular range. Asanother example, a set of quantized angular directions may be explicitlyindicated to the UE with the complete set of quantized angulardirections corresponding to individual angular directions in an absoluteway. This may represent a more complete representation of the region ofspace that the UE is indicated about because the lower bound of theangular direction, the upper bound of the angular direction, and theresolution of each angular direction is explicitly provided.

In some embodiments, beams refer to spatial filters. Spatial filters aresignal processing techniques applied by devices such as a UE, a T-TRP,or an NT-TRP for the purpose of directional communication, e.g. so thatthe UE or the T-TRP or NT-TRP can transmit or receive physical layersignals or channels in a certain region of space. In some embodiments,directional communication refers to communication where beamforming isused by devices such as a UE, a T-TRP, or an NT-TRP. In wirelesscommunications, such spatial filtering is used to e.g. focus energy in acertain region of space. One example of spatial filtering in wirelesscommunications is called digital precoding, where different physicallayer signals carrying data streams are transmitted using multipleantennas and the different antennas use different digital phase shiftssuch that when the physical layer signals are transmitted over the airusing the multiple antennas, the signal waves add up constructively in acertain region of space, e.g. where the UE is located. Another exampleof spatial filtering is analog beamforming where different physicallayer signals are transmitted using multiple antennas and the differentantennas use different analog phase shifts such that when the physicallayer signals are transmitted over the air using the multiple antennas,the signal waves add up constructively in a certain region of space,e.g. where the UE is located. Another example of spatial filtering ishybrid beamforming, which uses a combination of both digital and analogbeamforming to perform signal processing such that signal waves add upconstructively in a certain region of space.

In some embodiments, methods in which the T-TRP indicates an angulardirection used for communicating with a NT-TRP may be considered loweroverhead compared to implementing beam sweeping that involves the use ofmultiple beams in different directions.

The methods are not limited to an integrated terrestrial/non-terrestrialnetwork. More generally, the methods may be used by a first device toperform directional communication to communicate with a second device,e.g. using a receive beam and/or transmit beam pointed in the directionof the second device. An indication of the angular direction may bereceived by the first device, e.g. via an indication of BAI in the formof a quantized angular direction.

In one embodiment, there is provided a method that may include receivingan indication of a range of angular directions for communicating with adevice. The method may further include receiving an indication of aquantized angular direction from within the range. The method mayfurther include performing directional communication with the device onan angular direction based on the quantized angular direction. Thedirectional communication may be implemented using beamforming, e.g. areceive and/or transmit beam pointed in the quantized angular direction.In some embodiments, the method is performed by a UE and the device is aNT-TRP. In some embodiments, the indication of the quantized angulardirection is received from a T-TRP.

In another embodiment, there is provided method that may includetransmitting an indication of a range of angular directions for use byan apparatus to communicate with a device. The method may furtherinclude determining an angular direction between a first locationassociated with the apparatus and a second location associated with thedevice. The method may further include selecting, based on the angulardirection, a quantized angular direction from within the range ofangular directions. The method may further include transmitting anindication of the quantized angular direction. In some embodiments, theapparatus is a UE and the device is a NT-TRP.

In some embodiments, the methods described herein can be applied tocommunications between one or more of: UEs, base-stations, satellites,sensors, vehicles (e.g. cars, motorcycles, trucks, trains),reconfigurable intelligent surfaces (RIS) (also known as intelligentreflective surfaces (IRS), smart reflect-array, reconfigurablemeta-surface, holographic MIMO) and infrastructures. An indication of anangular direction can be received from any one of the above for thepurpose of directional communication on the indicated quantized angulardirection.

Systems for performing the methods are also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described, by way of example only, with reference tothe accompanying figures wherein:

FIG. 1 is a network diagram of an example communication system;

FIG. 2 is a block diagram of an example electronic device;

FIG. 3 is a block diagram of another example electronic device;

FIG. 4 is a block diagram of example component modules;

FIG. 5 is a block diagram of an example user equipment, T-TRP, andNT-TRP;

FIG. 6 illustrates a deployment of a NT-TRP, according to oneembodiment;

FIGS. 7 and 8 illustrate a beam direction defined in terms of zenithangle and azimuth angle, according to one embodiment;

FIGS. 9 and 10 illustrate implementation of a physical aerial channel(PACH), according to various embodiments;

FIG. 11 illustrates a deployment of two NT-TRPs, according to oneembodiment;

FIG. 12 illustrates a beam direction defined in terms of zenith angleand azimuth angle, according to another embodiment; and

FIGS. 13 to 17 are flow diagrams illustrating methods according tovarious embodiments.

DETAILED DESCRIPTION

For illustrative purposes, specific example embodiments will now beexplained in greater detail below in conjunction with the figures.

Example Communication Systems and Devices

FIG. 1 illustrates an example communication system 100. In general, thecommunication system 100 enables multiple wireless or wired elements tocommunicate data and other content. The purpose of the communicationsystem 100 may be to provide content, such as voice, data, video, and/ortext, via broadcast, narrowcast, user device to user device, etc. Thecommunication system 100 may operate by sharing resources, such asbandwidth.

In this example, the communication system 100 includes electronicdevices (ED) 110 a-110 c, radio access networks (RANs) 120 a-120 b, acore network 130, a public switched telephone network (PSTN) 140, theinternet 150, and other networks 160. Although certain numbers of thesecomponents or elements are shown in FIG. 1, any reasonable number ofthese components or elements may be included in the communication system100.

The EDs 110 a-110 c are configured to operate, communicate, or both, inthe communication system 100. For example, the EDs 110 a-110 c areconfigured to transmit, receive, or both via wireless or wiredcommunication channels. Each ED 110 a-110 c represents any suitable enduser device for wireless operation and may include such devices (or maybe referred to) as a user equipment/device (UE), wirelesstransmit/receive unit (WTRU), mobile station, fixed or mobile subscriberunit, cellular telephone, station (STA), machine type communication(MTC) device, personal digital assistant (PDA), smartphone, laptop,computer, tablet, wireless sensor, or consumer electronics device.

In FIG. 1, the RANs 120 a-120 b include base stations 170 a-170 b,respectively. Each base station 170 a-170 b is configured to wirelesslyinterface with one or more of the EDs 110 a-110 c to enable access toany other base station 170 a-170 b, the core network 130, the PSTN 140,the internet 150, and/or the other networks 160. For example, the basestations 170 a-170 b may include (or be) one or more of severalwell-known devices, such as a base transceiver station (BTS), a Node-B(NodeB), an evolved NodeB (eNodeB or eNB), a Home eNodeB, a gNodeB, atransmission point (TP), a site controller, an access point (AP), or awireless router. Any ED 110 a-110 c may be alternatively or additionallyconfigured to interface, access, or communicate with any other basestation 170 a-170 b, the internet 150, the core network 130, the PSTN140, the other networks 160, or any combination of the preceding. Thecommunication system 100 may include RANs, such as RAN 120 b, whereinthe corresponding base station 170 b accesses the core network 130 viathe internet 150.

The EDs 110 a-110 c and base stations 170 a-170 b are examples ofcommunication equipment that can be configured to implement some or allof the functionality and/or embodiments described herein. In theembodiment shown in FIG. 1, the base station 170 a forms part of the RAN120 a, which may include other base stations, base station controller(s)(BSC), radio network controller(s) (RNC), relay nodes, elements, and/ordevices. Any base station 170 a, 170 b may be a single element, asshown, or multiple elements, distributed in the corresponding RAN, orotherwise. Also, the base station 170 b forms part of the RAN 120 b,which may include other base stations, elements, and/or devices. Eachbase station 170 a-170 b transmits and/or receives wireless signalswithin a particular geographic region or area, sometimes referred to asa “cell” or “coverage area”. A cell may be further divided into cellsectors, and a base station 170 a-170 b may, for example, employmultiple transceivers to provide service to multiple sectors. In someembodiments there may be established pica or femto cells where the radioaccess technology supports such. In some embodiments, multipletransceivers could be used for each cell, for example usingmultiple-input multiple-output (MIMO) technology. The number of RAN 120a-120 b shown is exemplary only. Any number of RAN may be contemplatedwhen devising the communication system 100.

The base stations 170 a-170 b communicate with one or more of the EDs110 a-110 c over one or more air interfaces 190 using wirelesscommunication links e.g. radio frequency (RF), microwave, infrared (IR),etc. The air interfaces 190 may utilize any suitable radio accesstechnology. For example, the communication system 100 may implement oneor more channel access methods, such as code division multiple access(CDMA), time division multiple access (TDMA), frequency divisionmultiple access (FDMA), orthogonal FDMA (OFDMA), or single-carrier FDMA(SC-FDMA) in the air interfaces 190.

A base station 170 a-170 b may implement Universal MobileTelecommunication System (UMTS) Terrestrial Radio Access (UTRA) toestablish an air interface 190 using wideband CDMA (WCDMA). In doing so,the base station 170 a-170 b may implement protocols such as HSPA, HSPA+optionally including HSDPA, HSUPA or both. Alternatively, a base station170 a-170 b may establish an air interface 190 with Evolved UTMSTerrestrial Radio Access (E-UTRA) using LTE, LTE-A, and/or LTE-B. It iscontemplated that the communication system 100 may use multiple channelaccess functionality, including such schemes as described above. Otherradio technologies for implementing air interfaces include IEEE 802.11,802.15, 802.16, CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, IS-2000, IS-95,IS-856, GSM, EDGE, and GERAN. Other multiple access schemes and wirelessprotocols may be utilized.

The RANs 120 a-120 b are in communication with the core network 130 toprovide the EDs 110 a-110 c with various services such as voice, data,and other services. The RANs 120 a-120 b and/or the core network 130 maybe in direct or indirect communication with one or more other RANs (notshown), which might or might not be directly served by core network 130,and might or might not employ the same radio access technology as RAN120 a, RAN 120 b or both. The core network 130 may also serve as agateway access between (i) the RANs 120 a-120 b or EDs 110 a-110 c orboth, and (ii) other networks (such as the PSTN 140, the internet 150,and the other networks 160). In addition, some or all of the EDs 110a-110 c may include functionality for communicating with differentwireless networks over different wireless links using different wirelesstechnologies and/or protocols. Instead of wireless communication (or inaddition thereto), the EDs may communicate via wired communicationchannels to a service provider or switch (not shown), and to theinternet 150. PSTN 140 may include circuit switched telephone networksfor providing plain old telephone service (POTS). Internet 150 mayinclude a network of computers and subnets (intranets) or both, andincorporate protocols, such as IP, TCP, UDP. EDs 110 a-110 c may bemultimode devices capable of operation according to multiple radioaccess technologies, and incorporate multiple transceivers necessary tosupport such.

FIGS. 2 and 3 illustrate example devices that may implement the methodsand teachings according to this disclosure. In particular, FIG. 2illustrates an example ED 110, and FIG. 3 illustrates an example basestation 170. These components could be used in the communication system100 or in any other suitable system.

As shown in FIG. 2, the ED 110 includes at least one processing unit200. The processing unit 200 implements various processing operations ofthe ED 110. For example, the processing unit 200 could perform signalcoding, data processing, power control, input/output processing, or anyother functionality enabling the ED 110 to operate in the communicationsystem 100. The processing unit 200 may also be configured to implementsome or all of the functionality and/or embodiments described in moredetail herein. Each processing unit 200 includes any suitable processingor computing device configured to perform one or more operations. Eachprocessing unit 200 could, for example, include a microprocessor,microcontroller, digital signal processor, field programmable gatearray, or application specific integrated circuit.

The ED 110 also includes at least one transceiver 202. The transceiver202 is configured to modulate data or other content for transmission byat least one antenna 204 or Network Interface Controller (NIC). Thetransceiver 202 is also configured to demodulate data or other contentreceived by the at least one antenna 204. Each transceiver 202 includesany suitable structure for generating signals for wireless or wiredtransmission and/or processing signals received wirelessly or by wire.Each antenna 204 includes any suitable structure for transmitting and/orreceiving wireless or wired signals. One or multiple transceivers 202could be used in the ED 110. One or multiple antennas 204 could be usedin the ED 110. Although shown as a single functional unit, a transceiver202 could also be implemented using at least one transmitter and atleast one separate receiver.

The ED 110 further includes one or more input/output devices 206 orinterfaces (such as a wired interface to the internet 150). Theinput/output devices 206 permit interaction with a user or other devicesin the network. Each input/output device 206 includes any suitablestructure for providing information to or receiving information from auser, such as a speaker, microphone, keypad, keyboard, display, or touchscreen, including network interface communications.

In addition, the ED 110 includes at least one memory 208. The memory 208stores instructions and data used, generated, or collected by the ED110. For example, the memory 208 could store software instructions ormodules configured to implement some or all of the functionality and/orembodiments described herein and that are executed by the processingunit(s) 200. Each memory 208 includes any suitable volatile and/ornon-volatile storage and retrieval device(s). Any suitable type ofmemory may be used, such as random access memory (RAM), read only memory(ROM), hard disk, optical disc, subscriber identity module (SIM) card,memory stick, secure digital (SD) memory card, and the like.

As shown in FIG. 3, the base station 170 includes at least oneprocessing unit 250, at least one transmitter 252, at least one receiver254, one or more antennas 256, at least one memory 258, and one or moreinput/output devices or interfaces 266. A transceiver, not shown, may beused instead of the transmitter 252 and receiver 254. A scheduler 253may be coupled to the processing unit 250. The scheduler 253 may beincluded within or operated separately from the base station 170. Theprocessing unit 250 implements various processing operations of the basestation 170, such as signal coding, data processing, power control,input/output processing, or any other functionality. The processing unit250 can also be configured to implement some or all of the functionalityand/or embodiments described in more detail herein. Each processing unit250 includes any suitable processing or computing device configured toperform one or more operations. Each processing unit 250 could, forexample, include a microprocessor, microcontroller, digital signalprocessor, field programmable gate array, or application specificintegrated circuit.

Each transmitter 252 includes any suitable structure for generatingsignals for wireless or wired transmission to one or more EDs or otherdevices. Each receiver 254 includes any suitable structure forprocessing signals received wirelessly or by wire from one or more EDsor other devices. Although shown as separate components, at least onetransmitter 252 and at least one receiver 254 could be combined into atransceiver. Each antenna 256 includes any suitable structure fortransmitting and/or receiving wireless or wired signals. Although acommon antenna 256 is shown here as being coupled to both thetransmitter 252 and the receiver 254, one or more antennas 256 could becoupled to the transmitter(s) 252, and one or more separate antennas 256could be coupled to the receiver(s) 254. Each memory 258 includes anysuitable volatile and/or non-volatile storage and retrieval device(s)such as those described above in connection to the ED 110. The memory258 stores instructions and data used, generated, or collected by thebase station 170. For example, the memory 258 could store softwareinstructions or modules configured to implement some or all of thefunctionality and/or embodiments described above and that are executedby the processing unit(s) 250.

Each input/output device 266 permits interaction with a user or otherdevices in the network. Each input/output device 266 includes anysuitable structure for providing information to or receiving/providinginformation from a user, including network interface communications.

One or more steps of the embodiment methods provided herein may beperformed by corresponding units or modules, according to FIG. 4. FIG. 4illustrates units or modules in a device, such as in ED 110 or basestation 170. For example, a signal may be transmitted by a transmittingunit or a transmitting module. A signal may be received by a receivingunit or a receiving module. A signal may be processed by a processingunit or a processing module. The processing module may encompass theunits/modules described later, in particular the processor 210 orprocessor 260. Other units/modules may be included in FIG. 4, but arenot shown. The respective units/modules may be hardware, software, or acombination thereof. For instance, one or more of the units/modules maybe an integrated circuit, such as field programmable gate arrays (FPGAs)or application-specific integrated circuits (ASICs). It will beappreciated that where the modules are software, they may be retrievedby a processor, in whole or part as needed, individually or together forprocessing, in single or multiple instances as required, and that themodules themselves may include instructions for further deployment andinstantiation.

Additional details regarding the EDs 110 and the base stations 170 areknown to those of skill in the art. As such, these details are omittedhere for clarity.

FIG. 5 illustrates another example of an ED 110 and a base station 170.The ED 110 will hereafter be referred to as a user equipment (UE) 110 orapparatus 110. The base station 170 is a T-TRP and will hereafter bereferred to as T-TRP 170. Also shown in FIG. 5 is a NT-TRP 172.

The T-TRP 170 may be called other names in some implementations, such asa base station, a base transceiver station, a radio base station, anetwork node, a network device, a device on the network side, atransmit/receive node, a Node B, an evolved NodeB (eNodeB or eNB), agigabit NodeB (gNB), a relay station, a remote radio head, a terrestrialnode, a terrestrial network device, or a terrestrial base station. Insome embodiments, the parts of the T-TRP 170 may be distributed. Forexample, some of the modules of the T-TRP 170 may be located remote fromthe equipment housing the antennas of the T-TRP 170, and may be coupledto the equipment housing the antennas over a communication link (notshown). Therefore, in some embodiments, the term T-TRP 170 may alsorefer to modules on the network side that perform processing operations,such as determining the location of the UE 110, resource allocation(scheduling), message generation, and encoding/decoding, and that arenot necessarily part of the equipment housing the antennas of the T-TRP170. The modules may also be coupled to other T-TRPs. In someembodiments, the T-TRP 170 may actually be a plurality of T-TRPs thatare operating together to serve the UE 110, e.g. through coordinatedmultipoint transmissions.

The T-TRP 170 includes a transmitter 252 and a receiver 254 coupled toone or more antennas 256. Only one antenna 256 is illustrated. One,some, or all of the antennas may alternatively be panels. Thetransmitter 252 and the receiver 254 may be integrated as a transceiver.The T-TRP 170 further includes a processor 260 for performing operationsincluding those related to: preparing a transmission for downlinktransmission to the UE 110, processing an uplink transmission receivedfrom the UE 110, preparing a transmission for backhaul transmission toNT-TRP 172, and processing a transmission received over backhaul fromthe NT-TRP 172. Processing operations related to preparing atransmission for downlink or backhaul transmission may includeoperations such as encoding, modulating, precoding (e.g. MIMOprecoding), transmit beamforming, and generating the symbols fortransmission. Processing operations related to processing receivedtransmissions in the uplink or over backhaul may include operations suchas receive beamforming, and demodulating and decoding the receivedsymbols. The processor 260 may also perform operations relating tonetwork access (e.g. initial access) and/or downlink synchronization,such as generating the content of the synchronization signal blocks(SSBs) disclosed herein, generating the system information, etc. In someembodiments, the processor 260 also generates the indication of beamdirection, e.g. beam angle information (BAI) described herein, which maybe scheduled for transmission by scheduler 253. The processor 260performs other network-side processing operations described herein, suchas determining the location of the UE 110, determining where to deployNT-TRP 172, etc. In some embodiments, the processor 260 may generatesignaling, e.g. to configure one or more parameters of the UE 110 and/orone or more parameters of the NT-TRP 172. Any signaling generated by theprocessor 260 is sent by the transmitter 252. Note that “signaling”, asused herein, may alternatively be called control signaling. Dynamicsignaling may be transmitted in a control channel, e.g. a physicaldownlink control channel (PDCCH), and static or semi-static higher layersignaling may be included in a packet transmitted in a data channel,e.g. in a physical downlink shared channel (PDSCH).

The T-TRP 170 further includes a scheduler 253, which may scheduleuplink, downlink, and/or backhaul transmissions, including issuingscheduling grants and/or configuring scheduling free (“configuredgrant”) resources. The T-TRP 170 further includes a memory 258 forstoring information and data.

Although not illustrated, the processor 260 may form part of thetransmitter 252 and/or receiver 254. Also, although not illustrated, theprocessor 260 may implement the scheduler 253.

The processor 260, the scheduler 253, and the processing components ofthe transmitter 252 and receiver 254 may each be implemented by the sameor different one or more processors that are configured to executeinstructions stored in a memory, e.g. in memory 258. Alternatively, someor all of the processor 260, the scheduler 253, and the processingcomponents of the transmitter 252 and receiver 254 may be implementedusing dedicated circuitry, such as a programmed field-programmable gatearray (FPGA), a graphical processing unit (GPU), or anapplication-specific integrated circuit (ASIC).

The NT-TRP 172 is illustrated as a drone, but this is only an example.Also, the NT-TRP 172 may be called other names in some implementations,such as a non-terrestrial node, a non-terrestrial network device, or anon-terrestrial base station. The NT-TRP 172 includes a transmitter 272and a receiver 274 coupled to one or more antennas 280. Only one antenna280 is illustrated. One, some, or all of the antennas may alternativelybe panels. The transmitter 272 and the receiver 274 may be integrated asa transceiver. The NT-TRP 172 further includes a processor 276 forperforming operations including those related to: preparing atransmission for downlink transmission to the UE 110, processing anuplink transmission received from the UE 110, preparing a transmissionfor backhaul transmission to T-TRP 170, and processing a transmissionreceived over backhaul from the T-TRP 170. Processing operations relatedto preparing a transmission for downlink or backhaul transmission mayinclude operations such as encoding, modulating, precoding (e.g. MIMOprecoding), transmit beamforming, and generating the symbols fortransmission. Processing operations related to processing receivedtransmissions in the uplink or over backhaul may include operations suchas receive beamforming, and demodulating and decoding the receivedsymbols. In some embodiments, the processor 276 implements the transmitbeamforming and/or receive beamforming based on beam directioninformation (e.g. BAI) received from T-TRP 170. In some embodiments, theprocessor 276 may generate signaling, e.g. to configure one or moreparameters of the UE 110. Dynamic signaling may be transmitted in acontrol channel, e.g. a PDCCH, and static or semi-static higher layersignaling may be included in a packet transmitted in a data channel,e.g. in a PDSCH. In some embodiments, the processor 276 generates areference signal for transmission to UE 110 and/or for transmission toanother NT-TRP.

The NT-TRP 172 further includes a memory 278 for storing information anddata.

Although not illustrated, the processor 276 may form part of thetransmitter 272 and/or receiver 274.

The processor 276 and the processing components of the transmitter 272and receiver 274 may each be implemented by the same or different one ormore processors that are configured to execute instructions stored in amemory, e.g. in memory 278. Alternatively, some or all of the processor276 and the processing components of the transmitter 272 and receiver274 may be implemented using dedicated circuitry, such as a programmedFPGA, a GPU, or an ASIC. In some embodiments, the NT-TRP 172 mayactually be a plurality of NT-TRPs that are operating together to servethe UE 110, e.g. through coordinated multipoint transmissions.

In the embodiments described below, the NT-TRP 172 implements physicallayer processing, but does not implement higher layer functions such asfunctions at the medium access control (MAC) or radio link control (RLC)layer. This is only an example. More generally, the NT-TRP 172 mayimplement higher layer functions in addition to physical layerprocessing.

The UE 110 includes a transmitter 201 and a receiver 203 coupled to oneor more antennas 204. Only one antenna 204 is illustrated. One, some, orall of the antennas may alternatively be panels. The transmitter 201 andthe receiver 203 may be integrated as a transceiver, e.g. transceiver202 of FIG. 2. The UE 110 further includes a processor 210 forperforming operations including those related to preparing atransmission for uplink transmission to the NT-TRP 172 and/or T-TRP 170,and those related to processing downlink transmissions received from theNT-TRP 172 and/or T-TRP 170. Processing operations related to preparinga transmission for uplink transmission may include operations such asencoding, modulating, transmit beamforming, and generating the symbolsfor transmission. Processing operations related to processing downlinktransmissions may include operations such as receive beamforming,demodulating and decoding the received symbols. Depending upon theembodiment, a downlink transmission may be received by the receiver 203,possibly using receive beamforming, and the processor 210 may extractsignaling from the downlink transmission (e.g. by detecting and/ordecoding the signaling). An example of signaling may be a referencesignal transmitted by NT-TRP 172. In some embodiments, the processor 276implements the transmit beamforming and/or receive beamforming based onthe indication of beam direction, e.g. BAI, received from T-TRP 170. Insome embodiments, the processor 210 may perform operations relating tonetwork access (e.g. initial access) and/or downlink synchronization,such as operations relating to detecting a synchronization sequence,decoding and obtaining the system information, etc. In some embodiments,the processor 210 may perform channel estimation, e.g. using a referencesignal received from the NT-TRP 172.

Although not illustrated, the processor 210 may form part of thetransmitter 201 and/or receiver 203. The UE 110 further includes amemory 208 for storing information and data.

The processor 210, and the processing components of the transmitter 201and receiver 203 may each be implemented by the same or different one ormore processors that are configured to execute instructions stored in amemory (e.g. in memory 208). Alternatively, some or all of the processor210, and the processing components of the transmitter 201 and receiver203 may be implemented using dedicated circuitry, such as a FPGA, a GPU,or an ASIC.

The T-TRP 170, the NT-TRP 172, and/or the UE 110 may include othercomponents, but these have been omitted for the sake of clarity.

Deployment of NT-TRPs

In some embodiments a plurality of UEs may, by default, communicate witha network via a T-TRP. However, on an intermittent basis one or more ofthe UEs may instead or additionally communicate with the network via aNT-TRP. For example a NT-TRP may be deployed and communicate with one ormore UEs in particular circumstances, e.g. on an on-demand basis, suchas when there is high demand on the T-TRP, and/or when the wirelesscommunication link between the T-TRP and the one or more UEs is weak,and/or when communicating with the UE is high priority, e.g. due toquality of service (QoS) and/or user experience requirements. Forexample, if there is a temporary large congregation of UEs all served bya same T-TRP, e.g. when a crowd gathers in a small area, then a NT-TRPmay be deployed to offload some or all of the traffic demand beingplaced on the T-TRP.

FIG. 6 illustrates a deployment of NT-TRP 172, according to oneembodiment. The communication between UE 110 and T-TRP 170 is not aseffective because of the presence of a building 302. Therefore, the UE110 primarily communicates with NT-TRP 172 via wireless link 304. TheNT-TRP 172 may then communicate with T-TRP 170 over backhaul wirelesslink 306. In some embodiments, the NT-TRP 172 may relay signaling anddata between the UE 110 and the T-TRP 170. The wireless links 304 and306 may be line-of-sight (LOS), which may allow for more effectivecommunication.

In some embodiments, the NT-TRP 172 might be specifically deployed toonly communicate with UE 110. In other embodiments, the NT-TRP 172 mightbe specifically deployed to only communicate with a particular group ofUEs that includes UE 110. In other embodiments, the NT-TRP 172 might bedeployed to a particular region to serve any UEs that may be in thatregion. For example, the region may be one in which UE traffic demand isdetermined to be high. The UE 110 may happen to be in that region anddecides to, or is instructed to, communicate with NT-TRP 172.

In some embodiments, the network may determine that UE traffic demand ishigh in a particular region based on the quantity and/or density of UEslocated in that region. For example, the network may determine thelocation of each of a plurality of UEs being served by one or moreT-TRPs. Based on knowledge of the location of each of the UEs, thenetwork may determine that a large number of UEs exceeding a certainthreshold are in close proximity to each other. The region encompassingthose large number of UEs in close proximity may then be determined tobe a region in which UE traffic demand is high.

A non-exhaustive list of example ways in which a network may determinethe location of a UE is as follows:

-   -   GPS coordinates of the UE may be transmitted to the T-TRP 170,        and the GPS coordinates may then be used to determine the        location of the UE.    -   The use of positioning reference signals, e.g. the UE transmits        a positioning reference signal (PRS) to each of a plurality of        T-TRPs, and the network uses the known location of those T-TRPs        and the time difference between the times at which each PRS was        received in order to estimate the location of the UE. The        opposite may also occur, e.g. the plurality of T-TRPs each        transmit a respective PRS that is received by the UE, and then        the UE reports the time difference between the received PRSs to        the network, which is then used to estimate the location of the        UE.    -   UE positioning sensing by a T-TRP, e.g. using radio wave        measurements (e.g. radar), and/or acoustic measurements        (echolocation), and/or detecting Wi-Fi signals, and/or lidar        measurements, etc. For example, a T-TRP performs a beam sweep of        radio waves, e.g. radar, and receives a reflection back from a        particular direction having a strong reflective signal. The        reflected signal is interpreted as the presence of a UE and is        used to estimate the location of that UE.    -   Tracking a UE's previous one or more locations and, based at        least on that tracking data, predicting the location of the UE,        e.g. using artificial intelligence, such as a machine learning        algorithm in which the past locations of a UE are input into a        trained machine learning algorithm that returns a prediction of        the future or current location of that UE.    -   A UE periodically transmits a signal to a T-TRP, e.g. in reply        to an interrogator signal. The contents and/or strength and/or        direction of the signal is indicative of the location of the UE.    -   A UE senses its environment, e.g. using radio wave measurements        (e.g. radar), and/or acoustic measurements (echolocation),        and/or detecting Wi-Fi signals, and/or lidar measurements, etc.        The results of the sensing measurements provide an indication of        the environment surrounding the UE. Information relating to the        environment is then transmitted to the T-TRP and is used by the        network to estimate the location of the UE.

A location of a UE may be expressed in precise terms, e.g. particularGPS coordinates, or (x,y,z) coordinates in relation to a T-TRP. Alocation of a UE may instead be expressed in more general terms, e.g.within a particular or general area or region.

In some embodiments, the current location of UEs might not be used todetermine regions in which UE traffic demand is considered to be high.For example, patterns may have previously been detected by the networkand then subsequently used in order to predict or determine regions inwhich UE traffic demand is currently high. For example, traffic patternsmay be analyzed over the course of many days or weeks, and it may beobserved that a particular highway has high UE traffic demand between4-6 pm Monday to Friday and that a particular area of downtown has highUE traffic demand between 12 pm-1 pm Monday to Friday. UE traffic demandmay then subsequently be determined to be high during those days/times,regardless of how many UEs are actually located in those regions on anygiven day/time. In some embodiments, artificial intelligence algorithms,such as a machine learning algorithm, may be used to decide that aregion has (or may have) high UE traffic demand. For example, thetraining of the machine learning algorithm may uncover patterns betweenUE traffic demand in certain regions based on various input factors,such as weather, day of year, day of week, time of day, etc.Post-training, the machine learning algorithm may then be used todetermine or predict that a particular region has high UE trafficdemand. The determination might or might not also be made on the basisof number of UEs actually located in that region on that day/time.

If a NT-TRP 172 is to be deployed to a particular region, then thenetwork might determine where, specifically within that region, theNT-TRP 172 is to be located. In some embodiments, the NT-TRP 172 isinstructed to locate itself vertically above the center of the region.In some embodiments, artificial intelligence algorithms, such as amachine learning algorithm, may be used determine the position at whichthe NT-TRP 172 is to be specifically located within the region. Forexample, a machine learning algorithm may uncover patterns duringtraining, which are then used post-training to determine the position atwhich the NT-TRP 172 is to be located within the region. In someembodiments, network planning may also or instead be used to determinethe position at which the NT-TRP 172 is to be located within the region.For example, if a building is known to be located at a particular spotin the region, the NT-TRP 172 might be deployed at a location in theregion that is not directly above the building, e.g. so that more UEs inthe region have a direct line-of-sight (LOS) to the NT-TRP 172.

If a NT-TRP 172 is to communicate with a particular UE, e.g. UE 110,then in some embodiments the network may determine where to specificallylocate the NT-TRP 172 in relation to that UE 110. In some embodiments,the NT-TRP 172 may be located at a position in the sky that is predictedor determined to have good LOS communication with the UE 110. Anon-exhaustive list of example ways in which a network may determineWhere to specifically locate the NT-TRP 172 in relation to UE 110 is asfollows:

-   -   The network may instruct the NT-TRP 172 to position itself        vertically above the determined or estimated location of UE 110.    -   The LTE 110 senses its environment, e.g. using radio wave        measurements (e.g. radar), and/or acoustic measurements        (echolocation), and/or detecting Wi-Fi signals, and/or lidar        measurements, etc. The sensing indicates that certain directions        are clear, and other directions have obstructions. For example,        the UE 110 may transmit one or more radio waves, e.g. radar, and        receive a reflection back in some directions. The directions in        which reflections are received are determined to be directions        that are obstructed and therefore not LOS. The UE 110 provides        the results of the sensing to the network, e.g. by transmitting        the results to the T-TRP 170. The network instructs the NT-TRP        170 based on the results of the sensing. For example, the NT-TRP        170 is instructed to locate itself in a direction in relation to        UE 110 that was not determined to be obstructed.    -   The network may use network planning. For example, if UE 110 is        located adjacent a known building, then the NT-TRP 177 may be        instructed to locate itself away from the building.    -   Positioning sensing by the T-TRP 170 and/or by the NT-TRP 172,        e.g. using radio wave measurements (e.g. radar), and/or acoustic        measurements (echolocation), and/or detecting Wi-Fi signals,        and/or lidar measurements, etc. For example, the T-TRP 170        and/or the NT-TRP 172 performs a beam sweep of radio waves, e.g.        radar, and receives a reflection back from a particular        direction having a strong reflective signal. The fact that the        reflection has a relatively strong signal is interpreted as the        presence of a UE, and the direction of reflection indicates the        beam direction of the UE. The T-TRP 170 and/or NT-TRP 172 then        determines that the UE present in that direction is UE 110, e.g.        based on the known or expected location of UE 110, or another        method, e.g. the T-TRP 170 transmitting a request for the UE ID        in that beam direction and in response the UE 110 transmitting        its UE ID to the T-TRP 170. The NT-TRP 172 is then positioned in        the vicinity of UE 110 and specifically at a location such that        NT-TRP 172 is in the same direction, relative to UE 110, as the        strongest reflection received from UE 110.

In some of the examples above, the network uses the location of the UE110. Example ways in which the network may determine the location of aUE are explained earlier.

Beam Angle Information for Communicating with NT-TRPs

In some embodiments, the network transmits, to UE 110, an indication ofthe beam direction to use to communicate with NT-TRP 172. The indicationof beam direction may be used by the UE 110 to implement a receive beamfor receiving a downlink transmission from the NT-TRP 172. Theindication of beam direction may also or instead be used by the UE 110to implement a transmit beam for sending an uplink transmission to theNT-TRP 172.

In some embodiments, the indication of beam direction may be expressedexplicitly, e.g. via an absolute value, such as specifying an angle inrelation to one or more origin or reference points. For example, theindication may be expressed in terms of beam angle information (BAI),e.g. the angle of the beam in terms of azimuth angle and/or zenithangle. In the remaining embodiments, BAI will be used and expressed interms of azimuth and/or zenith angle in relation to a predefined origin.However, other methods of indicating beam direction are alsocontemplated, which might not include using the azimuth and/or zenithangle. For example, an indication of beam direction may be expressed interms of (x, y, z) coordinates, spherical coordinates, a 3D vector, etc.In some embodiments, the beam direction might only be indicated in a 2Dplane, e.g. only azimuth angle or only zenith angle or only (x, y)coordinates, etc.

In some embodiments, e.g. as described below in relation to FIGS. 7 to12, the BAI may be expressed as a quantized angular direction. Forexample, a range of angular directions in the form of a set of quantizedangular directions may be configured, and the BAI indicated is onequantized angular direction selected from the set of quantized angulardirections.

In some embodiments, the BAI is determined based on the known orpredicted location of UE 110 in relation to NT-TRP 172. For example, thenetwork determines the location of UE 110 using any one of the methodsdescribed earlier. The network also knows the location of NT-TRP 172,e.g. because the network instructed the NT-TRP 172 to fly to a specificlocation. The network can therefore determine the line-of-sight (LOS)direction between the location of UE 110 and the location of NT-TRP 172.The direction may be determined by comparing the location of the UE 110to the location of the NT-TRP 172, and expressing the difference betweenthe two locations in directional terms, e.g. in terms of azimuth and/orzenith angle. The LOS direction may therefore be expressed in terms ofBAI, e.g. in terms of azimuth angle and zenith angle. The BAI is thenused to implement transmit and/or receive beams for when the UE 110 andthe NT-TRP 172 are communicating with each other. For example, the BAImay be used by the UE 110 to implement a receive beam and/or a transmitbeam that is pointed in the direction of the NT-TRP 172. Additionally,or instead, the BAI may be used by the NT-TRP 172 to implement a receivebeam and/or transmit beam that is pointed in the direction of the UE110.

In some embodiments, the T-TRP 170 transmits the BAI to UE 110, and thenthe UE 110 uses the BAI to implement a receive beam in the directionspecified by the BAI in order to receive information from the NT-TRP172, e.g. to receive a synchronization signal transmitted from NT-TRP172 and/or to receive a reference signal transmitted by NT-TRP 172. Insome embodiments, the UE 110 may subsequently then implement a transmitbeam in the direction specified by the BAI to transmit information tothe NT-TRP 172.

In some embodiments, the BAI is expressed as a quantized angulardirection. The granularity of the BAI is a function of the level ofquantization used to represent the BAI. Different levels of quantizationmay allow for different levels of BAI accuracy or precision. In general,there is a trade-off between overhead (more bits) and BAI accuracy orprecision. In some embodiments, the BAI may be a bit representation ofan accurate, e.g. exact or near-exact, beam direction between UE 110 andNT-TRP 172. In other embodiments, the BAI may be a bit representation ofa general beam direction between UE 110 and NT-TRP 172, which may allowfor fewer bits to communicate BAI. In some embodiments, the number ofbits used to represent BAI may be configurable, e.g. using higher-layersignaling such as radio resource control (RRC) signaling or in a mediumaccess control (MAC) control element (CE).

In some embodiments, a predefined mapping exists between different beamangles or ranges of angles and different bit values. Then, on a dynamicbasis, the T-TRP 170 sends, to UE 110, the bit value corresponding tothe angle or range of angles that most closely corresponds to the beamdirection between the UE 110 and the NT-TRP 172. The bit value is theBAI expressed as a quantized angular direction. For example, FIG. 7illustrates a volume of space 352 in which a beam direction is definedin terms of zenith angle direction and azimuth angle direction. Theorigin for the zenith angle measurement is defined as the pointvertically above the location of UE 110. Selected zenith angles between−10 degrees and +10 degrees are each mapped to a respective different4-bit value in the manner shown in table 354. Mapping to zenith anglesbetween −10 to +10 degrees is only an example, e.g. a larger or smallerrange of zenith angles may be defined, depending upon how large or smallof a region the NT-TRPs may be located above a UE's upper hemisphere.Similarly, the specific quantization and mapping illustrated in table354 is only an example. A larger number of bits may be used for moregranularity, or a smaller number of bits may be used for lessgranularity. The origin for the azimuth angle measurement may be definedin relation to a particular direction, e.g. North or the direction ofthe T-TRP 170. The azimuth is partitioned into eight different angleranges, each range spanning 45 degrees. Each range of azimuth angles ismapped to respective different 3-bit value in the manner shown in table356. The exact bit value mapping, and the size of each range of azimuthangles, is only an example. For example, a larger number of bits may beused for more granularity, or a smaller number of bits may be used forless granularity. In general, there is a trade-off between overhead andgranularity/quantization. The predefined mappings shown in tables 354and 356 are stored in memory of the UE 110 and also stored in memory atthe network side, e.g. in T-TRP 170. The predefined mappings shown intables 354 and 356 may be fixed or configurable. If the predefinedmappings are configurable, then they might be configurable on asemi-static basis, e.g. in higher-layer signaling such as RRC signalingor in a MAC CE.

The mappings in tables 354 and 356 are an example of a set of quantizedangular directions defining a range of angular directions. For example,the set includes the 15 zenith quantized angular directions: −10 degrees(represented by bit value 1111), −8 degrees (represented by hit value1101), . . . , +8 degrees (represented by bit value 0101), and +10degrees (represented by bit value 0111). The set further includes the 8azimuth quantized angular directions: 0-44 degrees (represented by bitvalue 000), . . . , 315-359 degrees (represented by bit value 111). Insome embodiments, the set of quantized angular directions may includeonly table 354 or only table 356. The set may be signaledsemi-statically, e.g. in higher layer signaling, to LTE 110 and storedin the memory of UE 110. Then, the set is used on a dynamic basis, e.g.using DCI, to indicate a particular quantized angular direction fromwithin the set of quantized angular directions.

FIG. 8 illustrates an example of dynamic use of tables 354 and 356 inorder to communicate the BAI (in terms of quantized angular direction)to UE 110. Based on the location of UE 110 and NT-TRP 172, the networkdetermines that the beam direction between UE 110 and NT-TRP 172 is −8.5degrees in the zenith and 62 degrees in the azimuth. The zenith angle−8.5 degrees is closest to −8, and so table 354 is used by the networkto map −8.5 degrees to bit value 1101. The azimuth angle 62 degreesfalls within the range of 45-89 degrees, and so table 356 is used by thenetwork to map 62 degrees to the bit value 001. The pair (1101, 001) isthe BAI (in terms of quantized angular direction), which is thentransmitted to UE 110. The UE 110 then uses the pair (1101, 001) to mapto −8 degrees zenith direction and between 45-89 degrees azimuthdirection. The UE 110 then implements receive beamforming having areceive beam pointed in the direction of −8 degrees zenith and between45-89 degrees azimuth. In some embodiments, the UE 110 may steer thereceive beam to the middle of the 45-89 degrees range, e.g. 67.5 degreesazimuth direction.

Using the receive beam, the UE 110 may then attempt to receive atransmission from the NT-TRP 172. For example, the UE 110 may firstlocate one or more synchronization sequences transmitted from the NT-TRP172, and then use the one or more synchronization sequences tosynchronize with the NT-TRP 172 in the downlink. However, synchronizingwith the NT-TRP 172 might not be necessary in some embodiments, e.g. ifthe UE 110 is already synchronized with the T-TRP 170 and the downlinktiming of the T-TRP 170 and the NT-TRP 172 is the same. The UE 110 maynext detect a reference signal transmitted by the NT-TRP 172, e.g. inorder to perform channel estimation. The reference signal may be achannel state information reference signal (CSI-RS). In someembodiments, the T-TRP 170 may transmit, UE 110, an indication of thedownlink time-frequency resource at which the reference signaltransmitted by NT-TRP 172 is located. In other embodiments, thetime-frequency location of the reference signal may be predefined andalready known by the UE 110. In some embodiments, the T-TRP 170 maytransmit, to UE 110, an indication of the reference signal sequence ofthe reference signal transmitted by NT-TRP 172. In other embodiments,the reference signal sequence may be predefined or determined using thetransmission sent by the NT-TRP 172. In some embodiments, uponsynchronizing with the NT-TRP 172 and performing channel estimation, theUE 110 may subsequently receive other control information and/or datafrom the NT-TRP 172 on the receive beam. In some embodiments, the UE 110may subsequently send an uplink transmission to the NT-TRP 172, e.g. totransmit data or control information to the network. The UE 110 may sendthe uplink transmission on a transmit beam that is pointed in thedirection specified by the BAI.

In the example explained above in relation to FIG. 8, the receivebeamforming and/or transmit beamforming performed by the UE 110 is basedon the BAI received from the T-TRP 110. The receive beam and/or transmitbeam is pointed in the direction specified by the BAI. Because the BAIindicates the beam direction to/from NT-TRP 172, a single receive beamdirection and transmit beam direction is implemented by the UE 110,rather than the UE 110 implementing beam sweeping using multiple receiveand/or transmit beams. Overhead may therefore be reduced compared tobeam sweeping because, unlike beam sweeping, multiple receive and/ortransmit beam directions are avoided.

In some embodiments, a downlink channel may be used by the T-TRP 170 totransmit, to one or more UEs, information for establishing communicationwith a NT-TRP, e.g. BAI and/or an indication of the time-frequencyresource at which the reference signal from the NT-TRP 172 is located,etc. The downlink channel will be referred to herein as a physicalaerial channel (PACH), and it may be a control channel, a data channel,or have both a control channel component and a data channel component,e.g, control signaling that schedules the information in a data portionof the channel. Also, in some embodiments, the PACH may instead be afield or portion of another pre-existing downlink channel, e.g. the PACHmay be a field or portion of a. physical downlink control channel(PDCCH) and/or a physical downlink data channel, e.g. a broadcastchannel or a physical downlink shared channel (PDSCH).

FIG. 9 illustrates an implementation of a PACH, according to oneembodiment. In the example described in relation to FIG. 9, two NT-TRPs172 and 173 are deployed at different locations, each in LOScommunication with UE 110.

Time-frequency resources 412 are illustrated that are used for downlinktransmission from T-TRP 170. Time-frequency resources 414 are alsoillustrated that are used for downlink transmission from NT-TRP 172.Time-frequency resources 416 are further illustrated that are used fordownlink transmission from NT-TRP 173. In implementation, thetime-frequency resources 412, 414, and 416 might or might not partiallyor fully overlap with each other in time and/or in frequency. Forexample, the time frequency resources 414 and 416 may overlap in timeand frequency, but the downlink transmissions from each of NT-TRP 172and 173 may be spatially separated, e.g. if NT-TRP 172 and NT-TRP 173each implement transmit beams in different beam directions.

The downlink transmission sent by T-TRP 170 in time-frequency resources412 includes a synchronization signal block (SSB) 422, which is used byUEs to perform initial access and connect with the network. In someembodiments, a synchronization signal (SS) burst may be implemented bythe T-TRP 170 in which beam sweeping is used by the T-TRP 170 totransmit multiple SSBs, each in a different beam direction. However, forsimplicity only a single SSB 422 is illustrated in FIG. 9. BecauseNT-TRPs 172 and 173 are deployed, a PACH 424 is also transmitted fromT-TRP 170 in the downlink time-frequency resources 412. Prior totransmission of the PACH 424, the T-TRP 170 may transmit an indicationof whether a PACH will be present in a particular upcoming time period.For example, the T-TRP 170 might only transmit a PACH 424 when NT-TRPsare deployed in the vicinity of UEs being served by T-TRP 170. When thePACH 424 is to be transmitted, an indication in the downlink informs theUEs that the PACH 424 will be present. In some embodiments, theindication may be transmitted in the SSB 422. In some embodiments, theindication may be transmitted as part of system information (SI), e.g.in a master information block (MIB) in SSB 422 or in other SI such assystem information block 1 (SIB1). In some embodiments, the indicationmay indicate information such as the time-frequency resource at which tofind the PACH 424 or at which to find the downlink scheduling grant forthe PACH 424.

Devices such as TRPs (e.g. T-TRPs and NT-TRPs) and UEs receive variouskinds of physical layer signals. Some physical layer signals are signalsof interest, e.g. signals that are intended for the UE, whereas somephysical layer signals are not signals of interest, e.g. signals thatare not intended for the UE and are considered as interference. Devicessuch as TRPs and UEs will attempt to perform detection on signals ofinterest, where the task of detection refers to the device attempting tofind a given sequence on certain physical layer resources (e.g. time andfrequency). This task of detection may require the device to testseveral hypotheses across degrees of freedom such as the sequencelength, the location of physical layer resources, physical layer cellidentities in order to find the signal of interest. In someimplementations, after the physical layer signal of interest is found,the device attempts to measure the quality of the signal using e.g. thereference signal received power (RSRP) and if that signal's RSRP isabove a certain threshold, then the physical layer signal is consideredto be “detected”, otherwise it is not considered to be “detected”.

In the example illustrated in FIG. 9, the PACH 424 indicates, for eachof the deployed NT-TRPs in the vicinity of UE 110, the BAI to be usedfor beamforming to communicate with that NT-TRP. The PACH 424 alsoindicates the time-frequency resource at which a reference signal and/orsynchronization information is located in the downlink transmission fromeach NT-TRP.

For example, FIG. 9 illustrates information 428 transmitted in the PACH424. The information 428 includes, for each of NT-TRPs 172 and 173, theBAI to be used for communicating with that NT-TRP, as well as anindication of the time-frequency resource at which a reference signalfrom that NT-TRP is located. The BAI includes an indication of thezenith angle direction and the azimuth angle direction, each of which isindicated via a specific bit value using the mapping shown in FIG. 7.The time-frequency resource at which the reference signal transmitted bythe NT-TRP is located is indicated in terms of subframe number and slotnumber within that subframe. In some embodiments, time resources such asOFDM symbols within the slot are given by the slot number, frequencyresources such as subcarriers or groups of subcarriers are given by thecenter frequency of the reference signal and the bandwidth of thereference signal or are given by the lower-edge of the reference signaland the bandwidth of the reference signal. The time-frequency locationmay be indicated in other ways instead, e.g. expressed in terms ofnumber of OFDM symbols offset from a reference point. The referencepoint may be the start of a particular time duration, such as the startof a frame, subframe, slot, or min-slot.

In the example illustrated in FIG. 9, the BAI transmitted as part ofinformation 428 is specific to UE 110, e.g. it is based on the anglebetween the location of HE 110 and the location of each NT-TRP.Therefore, the BAI may possibly be transmitted in a UE-specific downlinktransmission. For example, the time-frequency resource in which the BAIis transmitted may be dedicated to UE 110, and/or the downlinktransmission carrying the BAI may include the UE identification (ID) ofUE 110, and/or the UE 110 may use its UE ID to unmask, e.g. unscramble,the CRC of control information that schedules the time-frequencylocation of the BAI. The time-frequency resource at which the referencesignal from the NT-TRP is located might not be specific to UE 110 andtherefore may possibly be broadcast to a group of UEs including UE 110.

In some embodiments, the BAI transmitted in information 428 might not bespecific to UE 110. For example, a group of UEs may be relatively closeto each other such that the network indicates the same BAI to all UEs inthe group. When the BAI is not specific to a particular UE, then theinformation 428 may be broadcast to a group of UEs. For example, thetime-frequency resources for transmitting the information 428 may beaccessed by all UEs in the group. The downlink transmission may includea group ID that uniquely identifies the group of UEs, and/or each UE inthe group may use the group ID to unmask, e.g. unscramble, the CRC ofcontrol information that schedules the information 428.

In the example illustrated in FIG. 9, NT-TRP 172 sends a downlinktransmission in downlink time-frequency resources 414. The downlinktransmission includes a periodic transmission of a synchronizationsignal (SS) and a reference signal (RS). The SS may be or include aprimary synchronization signal (PSS) and/or a secondary synchronizationsignal (SSS). The RS may be a CST-RS. The RS is transmitted in slot 4 ofsubframe 3 of each frame, as indicated in information 428 transmitted inPACH 424. NT-TRP 173 also sends a downlink transmission in downlinktime-frequency resources 416. The downlink transmission from NT-TRP 173also includes a periodic transmission of a SS and RS. The SS may be orinclude a PSS and/or a SSS. The RS may be a CST-RS. The RS istransmitted in slot 2 of subframe 5 of each frame, as indicated ininformation 428 transmitted in PACH 424. The frames transmitted byNT-TRP 172 and NT-TRP 173 are illustrated in FIG. 9 as beingsynchronized in time, but this is only an example and is not necessary.

FIG. 10 illustrates a variation of FIG. 9 in which the PACH 424 is abroadcast or groupcast channel carrying information 428 that indicates,to a plurality of UEs, the time-frequency resource at which the RS fromeach NT-TRP is located. UE-specific transmissions are then separatelyscheduled in the downlink to indicate, for each UE of the plurality ofUEs, the BAI to be used by that UE to communicate with the NT-TRP.Because the plurality of UEs are each at a different location inrelation to a given NT-TRP, the BAI information for each UE may bedifferent, although as mentioned earlier in some embodiments the sameBAI may be assigned to UEs all close to each other, possibly in abroadcast or groupcast channel. In the example illustrated in FIG. 10, aPDCCH 436 is used to schedule a UE-specific downlink transmission ofdata for UE 110 in a PDSCH 438. The data for UE 110 scheduled in thePDSCH 438 includes BAI for UE 110, as shown at 440. In a variation, theBAI for UE 110 may be transmitted in the PDCCH 436.

Using the PACH 424, e.g. as per the examples in FIGS. 9 and 10, mayallow for increased flexibility in terms of scheduling the referencesignals transmitted by the NT-TRPs. Rather than having certaintime-frequency resources fixed for transmitting reference signals fromNT-TRPs, the time-frequency location of a reference signal from a NT-TRPmay be dynamically or semi-statically determined by the network, andthen the time-frequency location indicated in the PACH 424.

In some of the embodiments above, e.g. in the examples illustrated inrelation to FIGS. 9 and 10, the BAI indicates both zenith angledirection and azimuth angle direction. In other embodiments, to saveoverhead, the BAI might only indicate zenith angle direction and notazimuth angle direction, or vice versa.

In some embodiments, if NT-TRP 172 and NT-TRP 173 are relatively closeto each other, the T-TRP 170 may indicate, to one or more UEs, BAI thatis to be used for beamforming for communication with both NT-TRP 172 andNT-TRP 173. For example, if in FIG. 9 NT-TRP 173 was close to NT-TRP172, then the information 428 in PACH 424 might only indicate the zenithand azimuth angle for NT-TRP 172 along with an indication that that BAIalso applies to communication with NT-TRP 173. In some embodiments, thetime-frequency resource at which the reference signal from NT-TRP 172 islocated may be the same as the time-frequency resource at which thereference signal from NT-TRP 173 is located, in which case a singleindication of the location may apply to both NT-TRPs 172 and 173. Forexample, the PACH 424 may include the reference signal location“(subframe 3, slot 4)” along with an indication that this referencesignal location applies for the downlink transmission from all NT-TRPs.

Beam Steering By the NT-TRPs

In some embodiments described above, the UE 110 uses BAI received fromthe T-TRP 170 in order to implement a receive beam and/or a transmitbeam in the direction of NT-TRP 172. In general, the NT-TRP 172 might ormight not also perform beamforming. If the NT-TRP 172 also implementsbeamforming, then in some embodiments the BAI sent to the UE 110, or avariation thereof, is also transmitted from the T-TRP 170 to the NT-TRP172 over backhaul, e.g. over link 306 of FIG. 6. The NT-TRP 172 may thenuse the BAI to implement a receive beam and/or a transmit beam in thedirection of the UE 110, e.g. so that there is beam correspondence. Insome embodiments, the same BAI sent to the LT 110 in the downlink fromthe T-TRP 170 is also transmitted to the NT-TRP 172 over backhaul. Forexample, in FIG. 9 the BAI “(1101, 001)” is transmitted from T-TRP 170to UE 110, which corresponds to −8 degrees zenith direction and 45-89degrees azimuth direction. The BAI “(1101, 001)” may also be transmittedto the NT-TRP 172, and the NT-TRP 172 may store the mappings shown intables 354 and 356 in order to translate “(1101, 001)” into a beamdirection. The NT-TRP 172 may then send a transmission to UE 110 using atransmit beam based on the BAI and/or receive a transmission from UE 110using a receive beam based on the BAI. The origin/reference point forthe zenith and azimuth angle measurements for the NT-TRP 172 may bedifferent from (and generally the opposite of) the origin/referencepoint for the UE 110, in order to ensure that the NT-TRP 172 steers itsbeam in the opposite direction of UE 110 to obtain beam correspondence.For example, the origin point for the zenith angle for NT-TRP 172 may bedirectly vertically below the NT-TRP 172. In other embodiments, BAI of adifferent form or value compared to UE 110 is transmitted to NT-TRP 172,but the BAI transmitted to NT-TRP 172 still corresponds to the BAItransmitted to UE 110 so that the beam steering performed by the NT-TRP172 has correspondence to the beam steering performed by UE 110.

In some embodiments, NT-TRPs may communicate with each other usingbeamforming. FIG. 11 illustrates a deployment of two NT-TRPs 172 and173, according to one embodiment. The UE 110 communicates with NT-TRP172 over wireless link 304, and the UE 110 communicates with NT-TRP 173over wireless link 305. Both are LOS connections. The wireless channelbetween the UE 110 and T-TRP 170 is not LOS and not of high qualitybecause of the presence of building 302. The T-TRP 170 communicates withNT-TRP 172 over backhaul wireless link 306. The NT-TRP 173 and NT-TRP172 communicate with each other over backhaul wireless link 307. Forexample, the NT-TRP 172 may relay information between the NT-TRP 173 andthe T-TRP 170. Although not shown, the NT-TRP 173 is also able todirectly communicate with the T-TRP 170, although the channel betweenNT-TRP 173 and T-TRP 170 might not be as strong as between NT-TRP 172and T-TRP 170 because the NT-TRP 173 is farther away from T-TRP 170.

In some embodiments, the T-TRP 170 indicates, to one or both of theNT-TRPs 172 and 173, information for establishing communication with theother NT-TRP, e.g. BAI and/or an indication of the time-frequencyresource at which the reference signal from the NT-TRP is located, etc.For example, the T-TRP 170 may indicate, to NT-TRP 172, the BAI to beused by NT-TRP 172 to implement a receive beam and/or transmit beam inthe direction of NT-TRP 173. The BAI may be transmitted on backhaulwireless link 306. The BAI may be computed by the network based on theknown location of the NT-TRPs 172 and 173. The network knows thelocation of both NT-TRP 172 and NT-TRP 173 because the networkinstructed the NT-TRP 172 and NT-TRP 173 to fly to their respectivelocations. The network may determine the LOS direction between thelocation of NT-TRP 172 and the location of NT-TRP 173. The LOS directionmay be expressed in terms of BAI, e.g. in terms of azimuth angledirection and zenith angle direction. The origin/reference point for theangle measurements may be different compared to the embodiments in whichBAI is sent to UE 110.

For example, FIG. 12 illustrates a volume of space 452 in which a beamdirection for NT-TRP 172 to communicate with NT-TRP 173 is defined interms of zenith angle direction and azimuth angle direction. The originfor the zenith angle measurement is defined as the point horizontally onthe horizon, which is different from the origin defined in relation toUE 110, e.g. in FIG. 7. Selected zenith angles between −10 degrees and+10 degrees are each mapped to a respective different 4-bit value in themanner shown in table 454. Mapping to zenith angles between −10 to +10degrees is only an example, e.g. a larger or smaller range of zenithangles may be defined. Similarly, the specific quantization and mappingillustrated in table 454 is only an example. A larger number of bits maybe used for more granularity, or a smaller number of bits may be usedfor less granularity. The origin for the azimuth angle measurement maybe defined in relation to a particular direction, e.g. North or thedirection of the T-TRP 170, and the origin may be the same as the origindefined in relation to UE 110 in FIG. 7. The azimuth is partitioned intoeight different angle ranges, each range spanning 45 degrees, Each rangeof azimuth angles is mapped to respective different 3-bit value in themanner shown in table 456. The exact bit value mapping, and the size ofeach range of azimuth angles, is only an example. For example, a largernumber of bits may be used for more granularity, or a smaller number ofbits may be used for less granularity. The predefined mappings shown intables 454 and 456 are stored in memory of the NT-TRP 172 and alsostored in memory at the network side, e.g. in T-TRP 170. The predefinedmappings shown in tables 454 and 456 may be fixed or configurable. Ifthe predefined mappings are configurable, then they might beconfigurable on a semi-static basis, e.g. in higher-layer signaling suchas RRC signaling or in a MAC CE. The predefined mappings shown in tables454 and 456 are examples of a set or sets of quantized angulardirections defining a range of angular directions.

In operation, the T-TRP 170 may compute the zenith and azimuth anglebetween NT-TRP 172 and NT-TRP 173 in order to obtain BAI, and then makeuse of tables 454 and 456 to communicate the BAI (in terms of quantizedangular direction) to NT-TRP 172. The NT-TRP 172 may then use the BAI toimplement a receive beam and/or transmit beam in the direction of NT-TRP173. For example, using the receive beam steered in the directionindicated by the BAI, the NT-TRP 172 may attempt to receive atransmission from the NT-TRP 173. For example, the NT-TRP 172 may firstlocate one or more synchronization sequences transmitted from the NT-TRP173, and then use the one or more synchronization sequences tosynchronize with the NT-TRP 173. However, synchronizing with the NT-TRP173 might not be necessary in some embodiments, e.g. if the NT-TRP 172and NT-TRP 173 are already synchronized with each other and the T-TRP170. The NT-TRP 172 may next detect a reference signal transmitted bythe NT-TRP 173, e.g. in order to perform channel estimation for thechannel between the two NT-TRPs. The reference signal may be a channelstate information reference signal (CSI-RS). In some embodiments, theT-TRP 170 may transmit, to NT-TRP 172, an indication of thetime-frequency resource at which the reference signal transmitted byNT-TRP 173 is located. In other embodiments, the time-frequency locationof the reference signal may be predefined and already known by theNT-TRP 172. In some embodiments, the T-TRP 170 may transmit, to NT-TRP172, an indication of the reference signal sequence of the referencesignal transmitted by NT-TRP 173. In other embodiments, the referencesignal sequence may be predefined or determined using the transmissionsent by the NT-TRP 173. In some embodiments, upon synchronizing with theNT-TRP 173 (as necessary) and performing channel estimation, the NT-TRP172 may subsequently receive other control information and/or data fromthe NT-TRP 173 on the receive beam. In some embodiments, the NT-TRP 172may subsequently send a backhaul transmission to the NT-TRP 173. TheNT-TRP 172 may send the backhaul transmission on a transmit beam that ispointed in the direction specified by the BAI.

In some embodiments, the BAI used for NT-TRP 172 to communicate withNT-TRP 173, and/or the indication of the time-frequency resource atwhich a RS from the NT-TRP 173 is located, may be indicated to NT-TRP172 in a PACH, or something similar, e.g. like in FIG. 9, except thePACH for NT-TRP 172 is transmitted over backhaul link 306.

In some embodiments, the NT-TRP 173 also implements beamforming andtherefore may also receive the BAI indicating the beam direction betweenNT-TRP 173 and NT-TRP 172 and steer a receive beam and/or transmit beamin the direction of NT-TRP 172. If the NT-TRP 173 implementsbeamforming, then in general the beam the NT-TRP 173 uses to communicatewith NT-TRP 172 is different from, and pointed in a different directionfrom, the beam used by the NT-TRP 173 to communicate with UE 110. Ingeneral, the reference signal transmitted by NT-TRP 173 for use by UE110 for channel estimation is different from the reference signaltransmitted by NT-TRP 173 for use by NT-TRP 172 for channel estimation.In general, the channel between the NT-TRP 173 and the UE 110 isdifferent from the channel between the NT-TRP 173 and NT-TRP 172.

Other Variations

In some embodiments described herein, the BAI is transmitted by T-TRP170 in a PACH. More generally, the BAI may be transmitted in dynamicsignaling or in higher layer signaling. An example of dynamic signalingis downlink control information (DCI). The PACH may be dynamicsignaling. An example of higher layer signaling is RRC signaling or aMAC CE. Similarly, the indication of time-frequency resource at which areference signal from a NT-TRP is located may be transmitted by T-TRP170 in dynamic signaling or in higher layer signaling.

In general, the type and/or format of synchronization signals and/orreference signals transmitted from one NT-TRP to another NT-TRP need notbe the same as the type and/or format of synchronization signals and/orreference signals transmitted from a NT-TRP to a UE. Also, in general,the type and/or format of synchronization signals and/or referencesignals transmitted from a NT-TRP to a UE need not be the same as thetype and/or format of synchronization signals and/or reference signalstransmitted from a T-TRP to a UE. For example, the T-TRP 170 maytransmit SSBs that each include a PSS, a SSS, and a broadcast channel.However, a NT-TRP might not transmit a SSB at all, or might transmit amodified version of an SSB, e.g. one that does not have a broadcastchannel.

In some embodiments, the BAI and/or other information, e.g. theindication of the time-frequency location of a reference signal, may betransmitted using different wireless technologies, e.g. using unlicensedspectrum, such as Wi-Fi. In some embodiments, the BAI and/or otherinformation may be transmitted by multiple T-TRPs, e.g. usingcoordinated multi-point transmission.

In some embodiments, a NT-TRP may repeat a transmission also sent by aT-TRP, which may be useful in high reliability scenarios. For example,important information for UE 110 may be transmitted both in a downlinktransmission from T-TRP 170 and in a downlink transmission from NT-TRP172.

In some embodiments, BAI may be determined by the UE 110 and used by theUE 110 to steer its receive beam or transmit beam, possibly independentof whether the UE 110 is communicating with a NT-TRP or a T-TRP. Forexample, the UE 110 may sense its environment, e.g. using radio wavemeasurements (e.g. radar), and/or acoustic measurements (echolocation),and/or detecting Wi-Fi signals, and/or lidar measurements, etc. Thesensing indicates that certain directions are clear, and otherdirections have obstructions. For example, the UE 110 may transmit oneor more radio waves, e.g. radar, and receive a reflection back in somedirections. The directions in which reflections are received aredetermined to be directions that are obstructed and therefore not LOS.The UE 110 then performs receive and/or transmit beamforming in adirection determined to not have an obstruction. The beamforming may beused to communicate with a T-TRP and/or a NT-TRP. The UE 110 mayoptionally also provide the results of the sensing to the network, e.g.by transmitting the results to the T-TRP 170. The network may then usethe results to instruct a T-TRP and/or a NT-TRP to communicate with UE110 using beamforming that implements a receive or transmit beam in adirection to UE 110 that was not determined to be obstructed.

In many of the embodiments above, the BAI is used for communicating witha NT-TRP, e.g. NT-TRP 172. However, this is not necessary. For example,the BAI may be for communicating with another device, such as a UE or aT-TRP. More generally, the concept of indicating a quantized angulardirection described herein, e.g. in relation to FIGS. 7, 8, and 12 andtables 354, 356, 454, and 456, are independent of whether NT-TRPs arepresent. The quantized angular direction may be used by a first device(e.g. apparatus, UE, network device etc.) to perform directionalcommunication (e.g. beamforming) to communicate with a second device.For example, the directional communication may be implemented viabeamforming, e.g. using a receive beam and/or transmit beam pointed inthe direction of the second device. The indication of the quantizedangular direction does not necessarily need to be transmitted by aT-TRP, but could be transmitted by any device, e.g. a UE, a networkdevice such as an NT-TRP or T-TRP, etc.

In some embodiments, the UE 110 indicates to the network the ability toreceive reference signals transmitted by NT-TRPs as part of itscapability report to the network. The capability report may be sent toT-TRP 170. A communication with the network may be via T-TRP 170. TheT-TRPs and NT-TRPs may be configured to transmit reference signals thatare based on different sequences occupying different time-frequencyresources.

In some embodiments, as part of its capability report to the network,the UE 110 indicates to the network the maximum number of referencesignals transmitted by NT-TRPs that the UE 110 can be configured todetect and measure. In some embodiments, the UE 110 may indicate to thenetwork the maximum number of reference signals transmitted by NT-TRPsthat the UE 110 can detect and measure in a given time-frequencyresource.

In some embodiments, as part of its capability report to the network,the UE 110 indicates to the network the maximum number of referencesignals transmitted by NT-TRPs that the UE 110 can be configured todetect and measure in a pool of reference signals that can betransmitted by T-TRPs and/or NT-TRPS. In some embodiments, the UE 110can indicate to the network the maximum number of reference signalstransmitted by NT-TRPs that the UE can detect and measure in a giventime-frequency resource concurrently with reference signals transmittedby T-TRPS in the same time-frequency resource.

In some embodiments, as part of its capability report to the network,the UE 110 indicates to the network the maximum number of BAIindications that can be configured for the UE 110. In one example, thenetwork can configure the UE 110 with one BAI indication for eachreference signal transmitted by a NT-TRP for the UE 110 to attempt todetect and measure. In another example, the network can configure the UE110 with one BAI indication that the UE 110 uses to detect and measureany reference signal transmitted by a NT-TRP.

In some embodiments, as part of its capability report to the network,the UE 110 indicates to the network the maximum number of quantizedangular directions that a set or range of quantized angular directionscan contain. For example, the UE 110 may indicate the maximum number ofentries that a BAI table can contain for azimuth/zenith angle directionindications. As an example, the network can configure the UE 110 with upto a number of bits equal to the logarithmic function in base 2 of themaximum number of entries supported for the BAI table. Examples of BAItables are tables 354, 356, 454, and 456.

In some embodiments, the UE 110 indicates to the network the maximumnumber of PACHs that can be indicated to the UE 110 in a synchronizationsignal as part of its capability report to the network. As an example,the network can configure a T-TRP to send synchronization signals (e.g.SS/PBCH blocks) indicating the presence of up to the maximum number ofPACHs supported by the UE 110.

In some embodiments, as part of its capability report to the network,the UE 110 indicates to the network the maximum number of sensingreference signals that the UE 110 can be configured to transmit for thepurpose of performing sensing measurements.

In some embodiments, as part of its capability report to the network,the UE 110 indicates to the network the maximum number of sensingreference signals that the UE 110 can be configured to transmit for thepurpose of performing sensing measurements from a pool of uplinkreference signals (e.g. sounding reference signals). In someembodiments, the UE 110 can additionally or alternatively indicate tothe network the maximum number of sensing reference signals that the UE110 can transmit in a given time-frequency resource concurrently withother uplink reference signals (e.g. sounding reference signals) in thesame time-frequency resource.

In some embodiments, as part of its capability report to the network,the UE 110 indicates to the network the maximal range of an angulardirection that the UE 110 supports. As an example, the network canconfigure the UE 110 to perform beamforming in the range of angulardirection that is indicated by the network, where the range can be up tothe maximal range supported by the UE 110. The UE 110 may determineusing e.g. pre-defined rules or methods how to determine individualquantized angular directions and map them to the indicated range ofangular directions.

Example Methods

FIG. 13 is a flow diagram illustrating a method performed by T-TRP 170,UE 110, and NT-TRP 172, according to one embodiment.

At step 501, the T-TRP 170 transmits a SSB. The SSB may be an SSBtransmitted on a beam of a downlink beam sweeping pattern implemented byT-TRP 170, e.g. as part of a synchronization signal (SS) burst.

At step 502, the UE 110 uses the SSB to synchronize with the T-TRP 170and connect to the network. Step 502 may include detecting asynchronization sequence, such as a PSS and/or SSS, to determinedownlink timing. Step 502 may further include detecting a referencesignal transmitted by the T-TRP 170, and using the reference signal toperform channel estimation for the downlink channel from the T-TRP 170.Step 502 may further include decoding system information transmitted bythe T-TRP 170, e.g. system information in a MIB and SIB 1.

In some embodiments, step 502 might not be performed for initial networkaccess, but step 502 may instead be performed by UE 110 to connect tothe network following a sleep or low power mode.

At step 506, the LIE transmits a positioning reference signal (PRS) toeach of a plurality of T-TRPS, including T-TRP 170. At step 508, theT-TRPs receiving the PRS, including T-TRP 170, forward the received PRSto a processor on the network side. The processor might or might not bepart of T-TRP 170. The processor uses the known location of the T-TRPsand the time difference between the times at which each PRS was receivedby UE 110 in order to determine the location of the UE 110. Thedetermined location may be an estimated location.

At step 510, the T-TRP 170 deploys NT-TRP 172 to a particular locationinstructed by the T-TRP 170. The particular location to which the NT-TRP172 is deployed may be selected based on the location of the UE 110. Atstep 512, the NT-TRP 172 flies to the deployed location. The NT-TRP 172is in LOS communication with UE 110.

At step 514, the T-TRP 170 transmits a PACH to UE 110. The PACH includesthe BAI representing the direction between UE 110 and NT-TRP 172, whichwas computed by the network using the location of HE 110 and NT-TRP 172.For example, the BAI may be an indication of zenith angle direction andazimuth angle direction, as described earlier. The PACH also includes anindication of a time-frequency resource at which a reference signal fromthe NT-TRP 172 is located in the downlink transmission from the NT-TRIP172. In some embodiments, prior to sending the PACH, the T-TRP 170transmits an indication that informs the UE 110 that a PACH will betransmitted in an upcoming time duration. The indication may indicatethe time-frequency resource of the PACH. The indication may be part ofthe MIB transmitted in an SSB, e.g. in the SSB transmitted in step 501.

At step 516, the UE 110 decodes the following from the PACH: the BAI,and the indication of the time-frequency resource at which the referencesignal from the NT-TRP 172 is located. At step 518, the HE 110 uses theBAI to implement receive beamforming in which a receive beam is steeredin the direction of the NT-TRP 172. The receive beam is pointed in thedirection indicated by the BAI.

At step 520, the NT-TRP 172 transmits a synchronization signal (SS). TheNT-TRP 172 also transmits the reference signal at the time-frequencyresource indicated in the PACH. At step 522, the UE 110 synchronizeswith the NT-TRP 172 using the SS. For example, the SS includes a SSsequence that is detected by the UE 110 and used to determine downlinktiming from the NT-TRP 172. The UE 110 also detects the reference signalfrom the NT-TRP 172 at the indicated time-frequency resource. Thereference signal is used to perform channel estimation for the downlinkchannel from the NT-TRP 172.

At step 524, the UE 110 performs uplink and/or downlink communicationwith the network via NT-TRP 172. If downlink communication is performed,then the UE 110 may use a receive beam pointed in the directionindicated by the BAI. If uplink communication is performed, then the UE110 may use a transmit beam pointed in the direction indicated by theBAI.

FIG. 14 illustrates a variation of FIG. 13 in which step 506 is replacedwith steps 503, 504, and 505. At step 503, the T-TRP 170 configures theUE 110 to perform sensing of the UE's environment. The configuration maybe transmitted dynamically, e.g. in downlink control information (DCI),or instead in higher-layer signaling, e.g. in RRC signaling. At step504, the UE 110 performs the UE sensing measurements described earlierto determine information about its surrounding environment, e.g. toobtain a map of the UE's 3D environment. In one embodiment, the UE 110may transmit radio waves, e.g. radar, in different directions and, basedon the reflections, determine which directions are clear and whichdirections have obstructions. Instead of radio waves, another technologymay be used instead, e.g. echolocation. At step 505, the results of thesensing are reported to the T-TRP 170. At step 508, the location of theUE 110 is determined based, at least in part, on the sensingmeasurements. For example, the network already has approximate knowledgeof the UE's location because the UE 110 is communicating with a certainT-TRP 170, which provides coverage for a certain coverage area. As anexample: in beam-based deployments such as in millimeter wave bands, aT-TRP would use several narrow beams to cover a certain coverage area.Additionally, the network also has geographic information about thegeography of the coverage area, for instance: the position of buildings,roads and other forms of infrastructure. As an example: sensingmeasurement reports from the UE 110 can show where the UE 110 detected(or not) ceilings, e.g. an outdoor UE would not be able to detect thembecause radio waves would never come back towards the UE, whereas anindoor UE would be able to detect ceilings. Coupled with the informationof the transmit beams that the UE 110 is able to detect from the T-TRP170 or that the UE 110 is using to communicate with the T-TRP 110, thenetwork may accurately determine the UE's location. This allows thenetwork to deploy NT-TRP 172 and send BAI information to the UE 110 sothat the UE 110 can attempt to detect and measure reference signals fromthe NT-TRP 170.

The other steps of FIG. 14 are the same as FIG. 13.

FIG. 15 is a flow diagram illustrating a method performed by a networkdevice and an apparatus, according to one embodiment. The network devicemay be or include the T-TRP 170. The network device may refer to adistributed device on the network side. For example, the network devicemay be the T-TRP 170 in FIG. 5, but the processor 260 and scheduler 253may be located within the network separate from, and in communicationwith, the transmitter 252 and the receiver 254. The apparatus may be UE110.

At step 602, the network device determines a first location associatedwith a location of the apparatus. The first location may be the locationof the apparatus itself, e.g. the location of the apparatus in terms ofGPS coordinates and/or the location measured in relation to a T-TRP.Example ways to determine the location of an apparatus, such as UE 110,are described earlier. Alternatively, the first location may be apredicted location of the apparatus, e.g. based on the last knownlocation of the apparatus. Alternatively, the first location may be alocation within or encompassing a region in which the apparatus isdetermined or predicted to be located. For example, the first locationmay be the center of a region that is determined or predicted to havehigh UE traffic demand, and that includes the apparatus.

At step 604, the network device instructs a NT-TRP to move, e.g. fly, toa second location. The second location is related to the apparatus or tothe region in which the apparatus is known or predicted to be located.The second location may be a particular location within a region, e.g.vertically above the center of a region, or at a particular locationwithin the region determined based on network planning, etc., asdescribed earlier. In some embodiments, the second location may be alocation specifically based on the location of the apparatus, e.g.vertically above the determined or estimated location of the apparatus,etc., as described earlier. When at the second location, the NT-TRP maybe in LOS communication with the first location and/or with theapparatus.

At step 606, the network device determines the angular direction betweenthe first location and the second location. The angular direction willbe referred to as the beam direction. The beam direction is determinedby comparing the first location to the second location, and expressingthe difference between the two locations in directional terms, e.g. interms of azimuth angle direction and/or zenith angle direction. Forexample, the beam direction may be the azimuth angle and zenith anglerepresenting the displacement of the second location from the firstlocation, or vice versa.

At step 608, the network device transmits, to the apparatus, anindication of the beam direction. The beam direction may be BAIexpressed as a quantized angular direction. The indication may be a bitvalue representing the quantized angular direction.

At step 610, the apparatus receives, from the network device, theindication of the beam direction. The beam direction is used forcommunicating with the NT-TRP. The beam direction indicates thedirection of the receive beam and/or transmit beam implemented by theapparatus to wirelessly communicate with the NT-TRP.

At step 612, the apparatus performs beamforming to receive, from theNT-TRP, a transmission on a receive beam pointed in the beam direction.The beamforming is receive beamforming that is implemented by performingsignal processing on the received signal from the NT-TRP. Based on theindication of beam direction, the signal processing operates on thereceived signal to cause the received signal to experience constructiveinterference in the beam direction.

In some embodiments, the apparatus also or instead performs beamformingto transmit, to the NT-TRP, a transmission on a transmit beam pointed inthe beam direction. The beamforming is transmit beamforming that isimplemented by performing signal processing on the signal to betransmitted. Based on the indication of beam direction, the signalprocessing operates to cause the transmitted signal to experienceconstructive interference in the beam direction.

In some embodiments, the method of FIG. 15 further includes receiving,from the network device, an indication of a time-frequency resource atwhich a reference signal from the NT-TRP is located. The method may thenfurther include the apparatus receiving, from the NT-TRP, the referencesignal at the time-frequency resource. The reference signal may bereceived on the apparatus's receive beam, e.g. on the receive beamimplemented in step 612.

In some embodiments, the indication of beam direction may be or includeBAI that is quantized and specifies an azimuth angle direction and/or azenith angle direction. The receive beam in step 612 may then be pointedin that azimuth angle direction and/or zenith angle direction. In someembodiments, the azimuth angle direction and/or a zenith angle directionmay be expressed as an exact direction, e.g. 45 degrees azimuth and/or−8 degrees zenith. In other embodiments, the azimuth angle directionand/or the zenith angle direction may be expressed as a range, e.g.45-89 degrees azimuth and/or −6 to −8 degrees zenith. If an azimuthangle direction and/or zenith angle direction is expressed as a range,then in implementation pointing the receive and/or transmit beam in thedirection may involve selecting a value within or representative of thatrange and pointing the beam in that direction. For example, if the BAIis a quantized value that specifies an azimuth angle direction of 45-89degrees, then the receive beam and/or transmit beam pointed in theazimuth angle direction may be the middle of the range: 67.5 degreesazimuth.

In some embodiments, a first plurality of bits is used to specify theazimuth angle direction, and a second plurality of bits is used tospecify the zenith angle direction, e.g. like the examples in FIGS. 7 to9. In some embodiments, each different azimuth angle directioncorresponds to a respective different bit value of the first pluralityof bits, like in table 356 of FIG. 7. In some embodiments, eachdifferent zenith angle direction corresponds to a respective differentbit value of the second plurality of bits, like in table 354 of FIG. 7.

In some embodiments, the indication of beam direction transmitted instep 608 is specific to the apparatus. For example, the indication ofthe beam direction may be based on both the location of the apparatusand the location of the NT-TRP, as is the case in step 606 because thefirst location is associated with the apparatus and the second locationis associated with the NT-TRP. In some embodiments, the indication ofthe beam direction is transmitted in an apparatus-specific downlinktransmission from the network device. An apparatus-specific transmissionmay mean one, some, or all of the following: the transmission is in atime-frequency resource dedicated to the apparatus, e.g. dynamicallyscheduled for the apparatus; and/or the transmission may be associatedwith an ID of the apparatus, e.g. the transmission may include an IDthat uniquely identifies the apparatus, and/or the transmission may bepartially or fully masked using the ID; and/or the transmission is forthe single apparatus and not for a group of apparatuses.

FIG. 15 illustrates example operations of both a network device and anapparatus. Example methods will now be explained separately from eachperspective of two devices.

FIG. 16 illustrates a method, according to one embodiment. In someembodiments, the method is performed by an apparatus. The apparatus maybe a UE or a NT-TRP, or another device. In some embodiments, the methodis performed by a circuit chip. At step 652, an indication of a range ofangular directions is received. For example, the range of angulardirections may be in the form of a set of quantized angular directions.An example of a set of quantized angular directions is the zenithangular directions and/or the azimuth angular directions indicated inthe examples in FIGS. 7 and 12. An example of a set of quantized angulardirections is the 15 quantized zenith angle directions in table 354 ofFIG. 7. In the example, a range of angular directions between −10degrees and +10 degrees zenith is configured, quantized into 15direction values within the range, each direction value represented by adifferent bit value, e.g. “1100” represents the angular direction −4degrees zenith, etc. The range of angular directions is forcommunicating with a device. In some of the examples explained earlier,including in FIG. 15, the device is a NT-TRP. However, more generallythe device does not have to be a NT-TRP. For example, the device may bea network device or a UE. A network device may be a NT-TRP or a T-TRP.In one example, the range of angular directions may be for receiveand/or transmit beamforming when communicating with a UE, or whencommunicating with a T-TRP.

At step 654, an indication of a quantized angular direction from withinthe range of angular directions is received. For example, the indicationmay have been selected, e.g. by a T-TRP, based on the locationassociated with (e.g. the location of) the apparatus compared to thelocation associated with (e.g. the location of) the device that theapparatus is to communicate with. In the example in FIG. 7, theindication may be one of the bit values in table 354 and/or one of thebit values in table 356. In the example in FIG. 12, the indication beone of the bit values in table 454 and/or one of the bit values in table456.

At step 656, directional communication with the device is performed onan angular direction that is based on the quantized angular direction.The directional communication may be implemented using beamforming. Forexample, the communication may be or include receiving a transmissionfrom the device, in which case the directional communication may bereceive beamforming in which a receive beam is implemented that pointsin the direction of the quantized angular direction. As another example,the communication may be or include sending a transmission to thedevice, in which case the directional communication may be transmitbeamforming in which a transmit beam is implemented that points in thedirection of the quantized angular direction.

In some embodiments, the device is a network device and the directionalcommunication is on an uplink and/or a downlink channel. In someembodiments, the device is a user equipment and the directionalcommunication is on a sidelink channel, e.g. using device-to-device(D2D) communication.

In some embodiments, the device is a NT-TRP, and performing thedirectional communication includes receiving, from the NT-TRP, atransmission on a receive beam pointed in the quantized angulardirection.

In some embodiments, the indication of the quantized angular directionis received from a T-TRP, although this is not necessary. For example,the indication could be received from a NT-TRP or a UE.

In some embodiments, the method is performed by an apparatus, and theindication of quantized angular direction is specific to the apparatusand based on both the location associated with (e.g. location of) theapparatus and the location associated with (e.g. location of) thedevice. The device may be a NT-TRP. In some embodiments, the indicationof quantized angular direction is received in an apparatus-specifictransmission, such as an apparatus-specific downlink transmission, e.g.from a T-TRP or another network device.

In some embodiments in which the device is an NT-TRP, an indication maybe received that is an indication of a time-frequency resource at whicha reference signal from the NT-TRP is located. A receive beam may thenbe used to receive, from the NT-TRP, the reference signal at thetime-frequency resource. The receive beam is (or is part of) thedirectional communication. The receive beam may be pointed in thequantized angular direction. The method may further include detectingthe reference signal from the NT-TRP.

In some embodiments, the indication of quantized angular directionspecifies an azimuth angle direction, e.g. if one of the bit values intable 356 or table 456 are sent. Although these tables indicate a rangeof azimuth angle directions, the quantized angular direction may be oneangle representative of or within that range. In some embodiments, theindication of quantized angular direction specifies a zenith angledirection, e.g. if one of the bit values in table 354 or table 454 aresent. In some embodiments, the indication of quantized angular directionspecifies both an azimuth angle direction and a zenith angle direction.For example, the indication may be zenith angle 1111 and azimuth angle000, representing an angular direction of −10 degrees zenith and 0-44degrees azimuth, e.g. as per the tables in FIGS. 7 and 12.

In some embodiments, a first plurality of bits is used to specify theazimuth angle direction, e.g. like in tables 356 and 456. In someembodiments, a second plurality of bits is used to specify the zenithangle direction, e.g. like in tables 354 and 454. In some embodiments,each different azimuth angle direction corresponds to a respectivedifferent bit value of the first plurality of bits, and/or eachdifferent zenith angle direction corresponds to a respective differentbit value of the second plurality of bits. An example are the tables inFIGS. 7 and 12.

In some embodiments, the indication of the range of angular directionsreceived in step 652 is received on a semi-static basis, e.g. in higherlayer signaling, such as RRC signaling or in a MAC CE. In someembodiments, the indication of the quantized angular direction receivedin step 654 is received on a dynamic basis, e.g. in dynamic signaling,such as in DCI. For example, the tables in FIGS. 7 and/or 12 may beconfigured on a semi-static basis and indicated in RRC signaling.Particular values within the tables may then be indicated on a dynamicbasis in DCI based on the relative location of the two entitiescommunicating with each other, e.g. based on the location of theapparatus in relation to the device.

In some embodiments, a system is provided to perform any of the methodsdescribed in relation to FIG. 16. The system may be or include anapparatus, e.g. a UE or a circuit chip. The system may include a memoryto store processor-executable instructions. The system may furtherinclude a processor to execute the processor-executable instructions tocause the processor to perform the methods described above in relationto FIG. 16. For example, receiving the indication of the range ofangular directions in step 652 may include the processor receiving theindication from or at a receiver, e.g. by processing a receivedtransmission from the network, such as decoding the indication in adownlink transmission received from a network device. Receiving theindication of a quantized angular direction in step 654 may include theprocessor receiving the indication from or at a receiver, e.g. byprocessing a received transmission from the network, such as decodingthe indication in a downlink transmission received from a networkdevice. Receiving may be performed by a receiver or, in the case of acircuit chip, received at or by the processor of the circuit chip. Asanother example, performing the directional communication in step 656may include the processor implementing receive beamforming and/ortransmit beamforming based on the quantized angular direction.

FIG. 17 illustrates a method, according to another embodiment. In someembodiments, the method is performed by a network device, e.g. a T-TRPor a NT-TRP. In other embodiments, the method is performed by a UE. Atstep 682, an indication of a range of angular directions is transmitted.For example, the range of angular directions may be in the form of a setof quantized angular directions. An example of a set of quantizedangular directions is the zenith angular directions and/or the azimuthangular directions indicated in the examples in FIGS. 7 and 12. Theindication is transmitted at least to an apparatus. The indication maybe transmitted in an apparatus-specific communication. The indicationmay instead be groupcast or broadcast and received by multipleapparatuses. The apparatus uses the range of angular directions tocommunicate with a device. The device may be a NT-TRP, a T-TRP, or a UE.

At step 684, an angular direction is determined. The angular directionmay be referred to as a beam direction. The angular direction is betweena first location associated with the apparatus and a second locationassociated with the device. The first location may be the location ofthe apparatus itself. Alternatively, the first location may be apredicted location of the apparatus, e.g. based on the last knownlocation of the apparatus. Alternatively, the first location may be alocation within or encompassing a region in which the apparatus isdetermined or predicted to be located. The second location may be thelocation of the device. The second location may be a particular locationwithin a region, e.g. vertically above the center of a region, or at aparticular location within the region determined based on networkplanning, etc. In some embodiments, the second location may be thelocation of the device, which is also a location specifically based onthe location of the apparatus, e.g. vertically above the determined orestimated location of the apparatus. The angular direction may bedetermined by comparing the first location to the second location, andexpressing the difference between the two locations in directionalterms, e.g. in terms of azimuth angle direction and/or zenith angledirection.

At step 686, a quantized angular direction from within the range ofangular directions is selected based on the angular direction determinedin step 684. The selecting may be implemented using a mapping, e.g. alook-up table, such as one or more look-up tables based on the exampletables in FIGS. 7 and/or 12. For example, the range of angulardirections may comprise the 15 quantized angular directions in table 354of FIG. 7. The angular direction determined at step 684 may be −9.7degrees zenith direction, as an example, and the selection may then beimplemented by mapping the angular direction −9.7 degrees zenith to theclosest quantized angular direction in table 354, which is −10 degrees.The quantized angular direction −10 degrees may be indicated bytransmitting its corresponding bit value 1111.

At step 686, the indication of the quantized angular direction istransmitted, e.g. to the apparatus for use by the apparatus to performdirectional communication (e.g. beamforming) to communicate with thedevice.

In some embodiments, the device is a network device or a user equipment.A network device may be a T-TRP or an NT-TRP.

In some embodiments, the device is a NT-TRP, and the method may includeinstructing the NT-TRP to move to the second location. For example, theNT-TRP may be instructed to move to the second location after step 682but before step 684.

In some embodiments, the indication of the quantized angular directionis specific to the apparatus. In some embodiments, the indication of thequantized angular direction is transmitted in an apparatus-specifictransmission, such as an apparatus-specific downlink transmission.

In some embodiments, an indication is transmitted that is an indicationof a time-frequency resource at which a reference signal from the deviceis located. The device may be an NT-TRP, T-TRP, or UE. The indicationmay be transmitted to the apparatus.

In some embodiments, the indication of quantized angular directionspecifies an azimuth angle direction and/or a zenith angle direction. Insome embodiments, a first plurality of bits is used to specify theazimuth angle direction. In some embodiments, a second plurality of bitsis used to specify the zenith angle direction. In some embodiments, eachdifferent azimuth angle direction corresponds to a respective differentbit value of the first plurality of bits, and/or each different zenithangle direction corresponds to a respective different bit value of thesecond plurality of bits.

In some embodiments, the indication of the range of angular directionsis transmitted on a semi-static basis, e.g. in higher layer signaling,such as RRC signaling or in a MAC CE. In some embodiments, theindication of the quantized angular direction is transmitted on adynamic basis, e.g. in dynamic signaling, such as in DCI.

In some embodiments, a system is provided to perform any of the methodsdescribed in relation to FIG. 17. The system may be or include a networkdevice, e.g. a T-TRP or a NT-TRP. The system may be or include a UE. Thesystem may be or include a circuit chip. The system may include a memoryto store processor-executable instructions. The system may furtherinclude a processor to execute the processor-executable instructions tocause the processor to perform the methods described above in relationto FIG. 17. For example, transmitting an indication of a range ofangular directions in step 682 may be implemented by incorporating theindication in signaling, e.g. encoding the indication and including theencoded indication in signaling, which is then sent using a transmitter.“Transmitting”, as used herein, may be transmitting by a transmitter or,in the case of a circuit chip, transmitting the indication for output atthe chip, to subsequently be sent to a transmitter for transmission. Asanother example, the determining an angular direction in step 684 may beperformed by the processor comparing the first location to the secondlocation, and expressing the difference between the two locations indirectional terms, e.g. in terms of azimuth angle direction and/orzenith angle direction. As another example, the selecting a quantizedangular direction in step 686 may be performed by the processorperforming the mapping described above in relation to step 686. Asanother example, the indication of the quantized angular direction instep 688 may be transmitted. by incorporating the indication insignaling, e.g. encoding the indication and including the encodedindication in signaling, which is then sent using a transmitter. Asmentioned above, the transmitting may be transmitting by a transmitteror, in the case of a circuit chip, transmitting the indication foroutput at the chip, to subsequently be sent to a transmitter fortransmission.

In some of the embodiments described herein, channel estimation isperformed using a reference signal, e.g. a reference signal that wastransmitted by a NT-TRP. In some embodiments, the channel estimation maybe performed using minimum mean square error (MMSE) or anothertechnique. The received reference signal may be expressed as thetransmitted reference signal multiplied by the channel and with thenoise added. The transmitted reference signal is known because thereference signal sequence is known, and therefore the recipient of thereference signal, e.g. the UE 110, can estimate the value of the channelusing the received reference signal and the transmitted referencesignal.

Conclusion

In some embodiments, a beam indication framework is introduced in thecontext of an integrated terrestrial/non-terrestrial network. In someembodiments, LOS based communication between UEs and NT-TRPs, and/orbetween two NT-TRPs, and/or between T-TRPs and NT-TRPs, may be possible.In some embodiments, accurate beam indication with low-overhead may bepossible. In some embodiments, beam management may be simplified becausethe UE is explicitly instructed about where to steer itsreceive/transmit beam. The UE might not need to perform beam sweeping tofind the indicated reference signal from the NT-TRP. In someembodiments, a NT-TRP may steer its receive/transmit beam based on theBAI associated with another NT-TRIP. The NT-TRP might not need toperform beam sweeping to find the indicated reference signal from theother NT-TRP.

Because of the deployment of NT-TRPs, edge-less mobility may beprovided. For example, a UE of interest may be instructed to communicatewith a NT-TRP. The NT-TRP may follow the UE and may perform cellhandover on the UE's behalf. The network may ensure that a UE can betransferred from one NT-TRP to another NT-TRP.

In some embodiments, sensing-aided beam management may be provided. A UEmay sense its environment and send sensing measurements of the UE's 3Denvironment back to the network, possibly allowing the network todetermine the optimal location to send NT-TRPs to serve UEs. UEs mayalso determine where to steer their transmit/receive beams based on thesensing measurements.

Although the present invention has been described with reference tospecific features and embodiments thereof, various modifications andcombinations can be made thereto without departing from the invention.The description and drawings are, accordingly, to be regarded simply asan illustration of some embodiments of the invention as defined by theappended claims, and are contemplated to cover any and allmodifications, variations, combinations or equivalents that fall withinthe scope of the present invention. Therefore, although the presentinvention and its advantages have been described in detail, variouschanges, substitutions and alterations can be made herein withoutdeparting from the invention as defined by the appended claims.Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

Moreover, any module, component, or device exemplified herein thatexecutes instructions may include or otherwise have access to anon-transitory computer/processor readable storage medium or media forstorage of information, such as computer/processor readableinstructions, data structures, program modules, and/or other data. Anon-exhaustive list of examples of non-transitory computer/processorreadable storage media includes magnetic cassettes, magnetic tape,magnetic disk storage or other magnetic storage devices, optical diskssuch as compact disc read-only memory (CD-ROM), digital video discs ordigital versatile disc (DVDs), Blu-ray Disc™, or other optical storage,volatile and non-volatile, removable and non-removable media implementedin any method or technology, random-access memory (RAM), read-onlymemory (ROM), electrically erasable programmable read-only memory(EEPROM), flash memory or other memory technology. Any suchnon-transitory computer/processor storage media may be part of a deviceor accessible or connectable thereto. Any application or module hereindescribed may be implemented using computer/processorreadable/executable instructions that may be stored or otherwise held bysuch non-transitory computer/processor readable storage media.

1. A method performed by an apparatus comprising: receiving anindication of a set of quantized angular directions within a range ofangular directions for communicating with a device, wherein the set ofquantized angular directions comprises a plurality of different bitvalues, each bit value specifying a respective different angle or rangeof angles; receiving an indication of a quantized angular direction fromwithin the range of angular directions, the indication of the quantizedangular direction comprising a particular bit value specifying aparticular angle or range of angles; and performing directionalcommunication with the device on an angular direction corresponding tothe particular angle or range of angles that was indicated to theapparatus.
 2. The method of claim 1, wherein performing directionalcommunication comprises performing receive beamforming and/or transmitbeamforming in the quantized angular direction.
 3. The method of claim2, wherein the device is a network device and the directionalcommunication is on an uplink and/or a downlink channel.
 4. The methodof claim 2, wherein the device is a user equipment and the directionalcommunication is on a sidelink channel.
 5. The method of claim 1,wherein the indication of the quantized angular direction is receivedfrom a terrestrial transmit-and-receive point (T-TRP).
 6. The method ofclaim 1, wherein the method is performed by a user equipment (UE),wherein the indication of quantized angular direction is specific to theUE and based on both the location of the UE and the location of thedevice, and wherein the indication of quantized angular direction isreceived in a UE-specific downlink transmission.
 7. The method of claim1, wherein the device is a non-terrestrial transmit-and-receive point(NT-TRP), wherein performing the directional communication comprisesreceiving, from the NT-TRP, a transmission on a receive beam pointed inthe quantized angular direction, and wherein the method furthercomprises: receiving an indication of a time-frequency resource at whicha reference signal from the NT-TRP is located; receiving on the receivebeam, from the NT-TRP, the reference signal at the time-frequencyresource; detecting the reference signal from the NT-TRP.
 8. The methodof claim 1, wherein the indication of quantized angular directionspecifies an azimuth angle direction and/or a zenith angle direction. 9.The method of claim 8, wherein a first plurality of bits is used tospecify the azimuth angle direction, and a second plurality of bits isused to specify the zenith angle direction, and wherein each differentazimuth angle direction corresponds to a respective different bit valueof the first plurality of bits, and wherein each different zenith angledirection corresponds to a respective different bit value of the secondplurality of bits.
 10. The method of claim 1, wherein the indication ofthe set of quantized angular directions is received on a semi-staticbasis, and wherein the indication of the quantized angular directionfrom within the range of angular directions is received on a dynamicbasis.
 11. An apparatus comprising: a memory to storeprocessor-executable instructions; a processor to execute theprocessor-executable instructions to cause the processor to: receive anindication of a set of quantized angular directions within a range ofangular directions for communicating with a device, wherein the set ofquantized angular directions comprises a plurality of different bitvalues, each bit value specifying a respective different angle or rangeof angles; receive an indication of a quantized angular direction fromwithin the range of angular directions, the indication of the quantizedangular direction comprising a particular bit value specifying aparticular angle or range of angles; and perform directionalcommunication with the device on an angular direction corresponding tothe particular angle or range of angles that was indicated to theapparatus.
 12. The apparatus of claim 11, wherein the processor is toperform directional communication by performing receive beamformingand/or transmit beamforming in the quantized angular direction.
 13. Theapparatus of claim 12, wherein the device is a network device and thedirectional communication is on an uplink and/or a downlink channel. 14.The apparatus of claim 12, wherein the device is a user equipment andthe directional communication is on a sidelink channel.
 15. Theapparatus of claim 11, wherein the indication of the quantized angulardirection is received from a terrestrial transmit-and-receive point(T-TRP).
 16. The apparatus of claim 11, wherein the apparatus comprisesa user equipment (UE), wherein the indication of quantized angulardirection is specific to the UE and based on both the location of the UEand the location of the device, and wherein the indication of quantizedangular direction is received in a UE-specific downlink transmission.17. The apparatus of claim 11, wherein the device is a non-terrestrialtransmit-and-receive point (NT-TRP), wherein the processor is to performdirectional communication by performing operations including receiving,from the NT-TRP, a transmission on a receive beam pointed in thequantized angular direction, and wherein upon execution of theprocessor-executable instructions, the processor is further to: receivean indication of a time-frequency resource at which a reference signalfrom the NT-TRP is located; receive on the receive beam, from theNT-TRP, the reference signal at the time-frequency resource; detect thereference signal from the NT-TRP.
 18. The apparatus of claim 11, whereinthe indication of quantized angular direction specifies an azimuth angledirection and/or a zenith angle direction.
 19. The apparatus of claim18, wherein a first plurality of bits is used to specify the azimuthangle direction, and a second plurality of bits is used to specify thezenith angle direction, and wherein each different azimuth angledirection corresponds to a respective different bit value of the firstplurality of bits, and wherein each different zenith angle directioncorresponds to a respective different bit value of the second pluralityof bits.
 20. The apparatus of claim 11, wherein the indication of theset of quantized angular directions is to be received on a semi-staticbasis, and wherein the indication of the quantized angular directionfrom within the range of angular directions is to be received on adynamic basis.